Continuously variable transmission

ABSTRACT

Inventive embodiments are directed to components, subassemblies, systems, and/or methods for continuously variable accessory drives (CVAD). In one embodiment, a skew-based control system is adapted to facilitate a change in the ratio of a CVAD. In another embodiment, a skew-based control system includes a skew actuator coupled to a carrier member. In some embodiments, the skew actuator is configured to rotate a carrier member of a CVT. Various inventive traction planet assemblies can be used to facilitate shifting the ratio of a CVT. In some embodiments, the traction planet assemblies include legs configured to cooperate with the carrier members. In some embodiments, a traction planet assembly is operably coupled to the carrier members. Embodiments of a shift cam and traction sun are adapted to cooperate with other components of the CVT to support operation and/or functionality of the CVT. Among other things, shift control interfaces for a CVT are disclosed.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/251,325, filed on Oct. 14, 2008, which is hereby incorporated byreference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The field of the invention relates generally to mechanical and/orelectro-mechanical power modulation devices and methods, and moreparticularly to continuously and/or infinitely variable, planetary powermodulating devices and methods for modulating power flow in a powertrain or drive, such as power flow from a prime mover to one or moreauxiliary or driven devices.

2. Description of the Related Art

In certain systems, a single power source drives multiple devices. Thepower source typically has a narrow operating speed range at which theperformance of the power source is optimum. It is preferred to operatethe power source within its performance optimizing operating speedrange. A driven device typically also has a narrow operating speed rangeat which the performance of the driven device is optimum. It is alsopreferred to operate the driven device within its performance optimizingoperating speed range. A coupling is usually employed to transfer powerfrom the power source to the driven device. Where a direct,non-modulating coupling couples the power source to the driven device,the driven device operates at a speed proportional to that of the powersource. However, it is often the case that the optimum operating speedof the driven device is not directly proportional to the optimumoperating speed of the power source. Therefore, it is preferred toincorporate into the system a coupling adapted to modulate between thespeed of the power source and the speed of the driven device.

Couplings between the power source and the driven devices can beselected such that the input speed from the power source is reduced orincreased at the output of a given coupling. However, in frequentlyimplemented systems, typical known power train configurations and/orcoupling arrangements allow at best for a constant ratio between theinput speed from the power source and the speed of power transfer to thedriven device. One such system is the so-called front end accessorydrive (FEAD) system employed in many automotive applications. In atypical FEAD system, the prime mover (usually an internal combustionengine) provides the power to run one or more accessories, such as acooling fan, water pump, oil pump, power steering pump, alternator, etc.During operation of the automobile, the accessories are forced tooperate at speeds that have a fixed relationship to the speed of theprime mover. Hence, for example, as the speed of the engine increasesfrom 800 revolutions per minute (rpm) at idle to 2,500 rpm at cruisingspeed, the speed of each accessory driven by the engine increasesproportionally to the increase in engine speed, such that someaccessories may be operating at varying speeds ranging between 1,600 rpmto 8,000 rpm. The result of such system configuration is that often anygiven accessory does not operate within its maximum efficiency speedrange. Consequently, inefficiencies arise from wasted energy duringoperation and oversizing of the accessories to handle the speed and/ortorque ranges.

Thus, there exists a continuing need for devices and methods to modulatepower transfer between a prime mover and driven devices. In somesystems, it would be beneficial to regulate the speed and/or torquetransfer from an electric motor and/or internal combustion engine to oneor more driven devices that operate at varying efficiency optimizingspeeds. In some current automotive applications, there is a need for apower modulating device to govern the front end accessory drive withinexisting packaging limits. The inventive embodiments of power modulatingdevices and/or drivetrains described below address one or more of theseneeds.

SUMMARY OF THE INVENTION

The systems and methods herein described have several features, nosingle one of which is solely responsible for its desirable attributes.Without limiting the scope as expressed by the claims that follow, itsmore prominent features will now be discussed briefly. After consideringthis discussion, and particularly after reading the section entitled“Detailed Description of Certain Inventive Embodiments” one willunderstand how the features of the system and methods provide severaladvantages over traditional systems and methods.

One aspect of the invention relates to a continuously variable accessorydrive (CVAD) having an accessory device and a continuously variabletransmission (CVT) coupled to the accessory device. The continuouslyvariable transmission has a group of traction planets. Each tractionplanet can be adapted to rotate about a tiltable axis. The CVAD alsoincludes a skew actuator operably coupled to the CVT. The skew actuatorcan be adapted to apply a skew condition to the CVT to tilt the axes ofthe traction planets.

Another aspect of the invention concerns a continuously variableaccessory drive (CVAD) having a group of traction planets arrangedangularly about a longitudinal axis of the CVAD. The CVAD can include agroup of planet axles. Each planet axle is operably coupled to eachtraction planet. Each planet axle defines a tiltable axis of rotationfor each traction planet. Each planet axle can be configured for angulardisplacement in a plane perpendicular to the longitudinal axis. Eachplanet axle can be configured for angular displacement in a planeparallel to the longitudinal axis. In one embodiment, the CVAD includesa first carrier member that is operably coupled to a first end of eachplanet axle. The first carrier member can be mounted about thelongitudinal axis. The CVAD includes a second carrier member that isoperably coupled to a second end of each planet axle. The second carriermember can be mounted about the longitudinal axis. The first and secondcarrier members are configured to rotate relative to each other aboutthe longitudinal axis.

Yet another aspect of the invention concerns a continuously variableaccessory drive (CVAD) having a rotatable input coaxial with alongitudinal axis of the CVAD. The CVAD has a variator coaxial with thelongitudinal axis and coupled to the rotatable input. The variator has arotatable output. The CVAD has a planetary gear assembly coupled to therotatable output. The planetary gear assembly is configured to power anaccessory device. In one embodiment, the variator includes a group oftraction planets arranged angularly about the main shaft. The variatorcan include a first carrier member that is operably coupled to each ofthe traction planets. The variator can also include a second carriermember that is operably coupled to each of the traction planets. Thesecond carrier member is configured to rotate relative to the firstcarrier member to thereby apply a skew condition on each of the planetaxles.

One aspect of the invention concerns a continuously variable accessorydrive (CVAD) having a group of traction planets arranged angularly abouta longitudinal axis of the CVAD. In one embodiment, the CVAD includes agroup of planet axles operably coupled to each traction planet. Eachplanet axle defines a tiltable axis of rotation for each tractionplanet. Each planet axle can be configured for angular displacement in aplane perpendicular to the longitudinal axis. Each planet axle can beconfigured for angular displacement in a plane parallel to thelongitudinal axis. In one embodiment, the CVAD includes a first carriermember arranged coaxial about the longitudinal axis. The first carriermember can be operably coupled to each traction planet. The firstcarrier member can have a number of radially offset slots arrangedangularly about a center of the first carrier member. Each of theradially offset slots has a linear offset from a centerline of thecarrier member. The CVAD can include a second carrier member arrangedcoaxial about the longitudinal axis. The second carrier member can havea number of radial slots. The radial slots can be arranged angularlyabout a center of the second carrier member. Each of the radial slotsare substantially radially aligned with the center of the second carriermember. The CVAD can also include a skew actuator that is operablycoupled to at least one of the first and second carrier members. Theactuator can be configured to impart a relative rotation between thefirst and second carrier members.

Another aspect of the invention relates to a method of facilitatingcontrol of the speed ratio of a continuously variable accessory drive(CVAD). In one embodiment, the method includes the step of providing agroup of traction planets. The method includes the step of providingeach of the traction planets with a planet axle. Each traction planetcan be configured to rotate about a respective planet axle. The methodcan include the step of providing a first carrier member that isconfigured to engage a first end of each of the planet axles. The firstcarrier member can be mounted along a longitudinal axis of the CVAD. Themethod can include the step of providing a second carrier member that isconfigured to engage a second end of each of the planet axles. Thesecond carrier member can be mounted coaxially with the first carriermember. The method can also include the step of arranging the firstcarrier member relative to the second carrier member such that duringoperation of the CVAD the first carrier member can be rotated relativeto the second carrier member about the longitudinal axis.

Another aspect of the invention concerns a variator having a group oftraction planets arranged angularly about a longitudinal axis. In oneembodiment, the variator has a first carrier member that is arrangedcoaxial about the longitudinal axis. The first carrier member can beoperably coupled to each traction planet. The first carrier member canhave a number of radially offset slots that are arranged angularly abouta center of the first carrier member. In one embodiment, each of theradially offset slots has a linear offset from a centerline of thecarrier member. The variator can also have a second carrier member thatis arranged coaxial about the longitudinal axis. The second carriermember can have a number of radial slots. In one embodiment, the radialslots are arranged angularly about a center of the second carriermember. Each of the radial slots are substantially radially aligned withthe center of the second carrier member. The variator can also have atraction sun assembly radially inward of, and in contact with, eachtraction planet. The traction sun assembly can contact the first andsecond carrier members. The traction sun assembly is substantially fixedalong the longitudinal axis.

Another aspect of the invention relates to a method of assembling adevice for modulating power to an accessory device. The method includesthe steps of providing a continuously variable transmission (CVT) havinga group of traction planets arranged angularly about a longitudinalaxis. In one embodiment, the CVT has a skew-based control system adaptedto apply a skew condition to each of the traction planets. The methodalso includes the step of operably coupling the CVT to the accessorydevice.

Yet one more aspect of the invention addresses a variator having a groupof traction planets that are arranged angularly about a longitudinalaxis. In one embodiment, the variator includes a first carrier memberthat is arranged coaxial about the longitudinal axis. The first carriermember can be operably coupled to each traction planet. The firstcarrier member has a number of radially offset slots that are arrangedangularly about a center of the first carrier member. Each of theradially offset slots has a linear offset from a centerline of thecarrier member. The variator can include a second carrier member that isarranged coaxial about the longitudinal axis. In one embodiment, thesecond carrier member has a number of radial slots. The radial slots canbe arranged angularly about a center of the second carrier member. Eachof the radial slots are substantially radially aligned with the centerof the second carrier member. The variator can also include a tractionsun located radially inward of, and in contact with, each tractionplanet. The traction sun has an outer periphery provided with a firstand a second contact surface. The first and second contact surfaces canbe configured to contact each of the traction planets.

In another aspect, the invention concerns a variator having a group oftraction planets that are arranged angularly about a longitudinal axis.In one embodiment, the variator has a planet axle operably coupled toeach traction planet. The planet axle can be configured to provide atiltable axis of rotation for each traction planet. The variator caninclude a first carrier member that is arranged coaxially about thelongitudinal axis. The first carrier member can be operably coupled to afirst end of the planet axle. The variator can include a second carriermember that is arranged coaxially about the longitudinal axis. Thesecond carrier member can be operably coupled to a second end of theplanet axle. The variator can also include a carrier retaining ring thatis coupled to the first and second carrier members. The carrierretaining ring can be substantially non-rotatable about the longitudinalaxis. The carrier retaining ring can be configured to axially couple thefirst and second carrier members. The first carrier member is configuredto rotate with respect to the second carrier member to thereby apply askew condition on each of the planet axles.

One aspect of the invention relates to a variator having a group oftraction planets that are arranged angularly about a longitudinal axis.The variator includes a first carrier member that is coaxial with thelongitudinal axis. In one embodiment, the variator includes a secondcarrier member coaxial with the longitudinal axis. The variator caninclude a skew driver coupled to the first and second carrier members.The skew driver can be adapted to rotate the first carrier member in afirst rotational direction about the longitudinal axis. The skew drivercan be adapted to rotate the second carrier member in a secondrotational direction about the longitudinal axis. The first rotationaldirection is substantially opposite to the second rotational direction.

Another aspect of the invention relates to a method of adjusting a speedratio of a continuously variable accessory drive (CVAD) having a groupof traction planets. Each traction planet has a tiltable axis ofrotation. In one embodiment, the CVAD has a carrier member operablycoupled to each of the traction planets. The method can include the stepof determining a set point for an angular displacement of the carriermember. The set point for the angular displacement of the carrier memberis based at least in part on a set point for the speed ratio. The methodincludes the step of rotating the carrier member to the set point forthe angular displacement of the carrier member. Rotating the carriermember induces a skew condition on each tiltable axis of rotation. Thecarrier member is configured to adjust the skew condition as eachtiltable axis of rotation tilts. Rotating the carrier member comprisesactuating a skew actuator.

Yet one more aspect of the invention addresses a method of adjusting aspeed ratio of a continuously variable accessory drive (CVAD) having agroup of traction planets. Each traction planet has a tiltable axis ofrotation. The CVAD has a skew actuator operably coupled to each of thetraction planets. In one embodiment, the method includes the step ofdetermining a skew actuator command signal. The skew actuator commandsignal is based at least in part on a set point for the tilt angle. Themethod also includes the step of applying the skew actuator commandsignal to the skew actuator to thereby adjust the skew condition of thetraction planets.

One aspect of the invention concerns a method of adjusting a speed ratioof a continuously variable accessory drive (CVAD) having a group oftraction planets. Each traction planet has a tiltable axis of rotation.The CVAD has a skew actuator operably coupled to each of the tractionplanets. In one embodiment, the method includes the step of determininga skew actuator command signal. The command signal is based at least inpart on a set point for the desired speed. The method also includes thestep of applying the skew actuator command signal to the skew actuatorto thereby adjust the skew condition of the traction planets.

One aspect of the invention relates to a traction planet assembly havinga traction planet with a central bore. The traction planet assembly canhave a planet axle arranged in the central bore. The planet axle has afirst end and a second end. In one embodiment, the traction planetassembly has a first leg coupled to the first end of the planet axle.The first leg can be substantially non-rotatable with respect to theplanet axle. The traction planet assembly can have a second leg that iscoupled to the second end of the planet axle. The second leg can besubstantially rotatable with respect to the planet axle.

Another aspect of the invention concerns a traction planet assemblyhaving a traction planet with a central bore. In one embodiment, thetraction planet assembly has a planet axle that is arranged in thecentral bore. The planet axle can have a first end and a second end. Thefirst and second ends can be provided with inner bores. The tractionplanet assembly can have a shift reaction ball that is received in eachof the inner bores. In one embodiment, the traction planet assembly hasa first leg that is coupled to the first end of the planet axle. Thetraction planet assembly can also have a second leg that is coupled tothe second end of the planet axle. The first and second legs areprovided with tapered sides.

Yet another aspect of the invention involves a traction sun assembly fora continuously variable transmission (CVT) having a group of tractionplanet assemblies. The traction sun assembly includes a traction sunthat is coaxial with a longitudinal axis of the CVT. The traction suncan be radially inward of, and in contact with, each of the tractionplanet assemblies. In one embodiment, the traction sun assembly includesa shift cam that is operably coupled to the traction sun. The tractionsun assembly can also include a group of anti-rotation inserts attachedto the shift cam.

One aspect of the invention concerns a carrier member for a continuouslyvariable transmission (CVT) having a group of traction planets. Thecarrier member can have a substantially bowl-shaped body with a centralbore. In one embodiment, the carrier member can have a number ofradially offset slots arranged angularly about the central bore. Each ofthe radially offset slots can have a linear offset from a centerline ofthe bowl-shaped body.

In another aspect, the invention concerns a skew actuator for acontinuously variable transmission (CVT) having a skew control system.The skew actuator can have a hydraulic piston coupled to the CVT. In oneembodiment, the skew actuator has a hydraulic control valve in fluidcommunication with the hydraulic piston. The skew actuator can also havea spool actuator that is coupled to the hydraulic control valve. Thespool actuator can be configured to adjust the hydraulic control valvebased at least in part on a desired skew condition of the CVT.

Another aspect of the invention relates to a skew control system for acontinuously variable accessory drive (CVAD) having a group of tractionplanets. The skew control system includes a sensor configure to receivedata from a CVAD. The skew control system can include a skew actuatorconfigured to communicate with a control module. The skew actuator canbe further configured to apply a skew condition to each of the tractionplanets in a CVAD. The skew control system can also include a skewcontroller in communication with the control module. The skew controllercan be configured to determine a skew actuator command signal based atleast in part on a signal from the sensor. The skew actuator commandsignal is configured to control an output speed of a CVAD.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view of an inventive embodiment of acontinuously variable accessory drive (CVAD) having a skew controlsystem.

FIG. 2 is a cross-sectional perspective view of a continuously variabletransmission (CVT) that can be used with the CVAD of FIG. 1.

FIG. 3 is an exploded perspective view of the CVT of FIG. 2.

FIG. 4 is a cross-sectional view of the CVT of FIG. 2.

FIG. 5 is a partial cross-sectional perspective view of a variatorsubassembly that can be used in the CVT of FIG. 2.

FIG. 6 is a cross-sectional view of certain components of the CVT ofFIG. 2.

FIG. 7 is a cross-sectional Detail view A of certain components of thevariator subassembly of FIG. 5.

FIG. 8 is a perspective view of a carrier retaining ring that can beused with the variator subassembly of FIG. 5.

FIG. 9 is a perspective view of an inventive embodiment of a clevismember that can be used with the CVT of FIG. 2.

FIG. 10 is a perspective view of an inventive embodiment of a carriermember that can be used with the variator subassembly of FIG. 5.

FIG. 11 is a cross-sectional view of a traction planet assembly that canbe used with the variator subassembly of FIG. 5.

FIG. 12A is a perspective view of an inventive embodiment of a leg thatcan be used in the traction planet assembly of FIG. 11.

FIG. 12B is a cross-section view A-A of the leg of FIG. 12A.

FIG. 13 is a cross-sectional perspective view of a traction sun assemblythat can be used with the variator subassembly of FIG. 5.

FIG. 14 is an exploded, cross-sectional, perspective view of thetraction sun assembly of FIG. 13.

FIG. 15 is a cross-sectional view of an inventive embodiment of acontinuously variable transmission (CVT) having a skew-based controlsystem.

FIG. 16 is a perspective view of a variator subassembly of the CVT ofFIG. 15.

FIG. 17 is a cross-sectional view of the variator subassembly of FIG.16.

FIG. 18 is an exploded-perspective view of the variator subassembly ofFIG. 16.

FIG. 19 is a plan view of the variator subassembly of FIG. 16.

FIG. 20A is a plan view of an inventive embodiment of a carrier memberthat can be used with the variator subassembly of FIG. 16.

FIG. 20B is a cross-sectional view of the carrier member of FIG. 20A.

FIG. 20C is a perspective view of the carrier member of FIG. 20A.

FIG. 21A is a plan detail view B of a radially offset slot of thecarrier member of FIG. 20A.

FIG. 21B is a schematic illustration of the radially offset slot of FIG.21A.

FIG. 21C is another schematic illustration of the radially offset slotof FIG. 21A.

FIG. 21D is yet another schematic illustration of the radially offsetslot of FIG. 21A.

FIG. 21E is a plan view of another embodiment of a radially offset slotof the carrier member of FIG. 20A.

FIG. 21F is a schematic illustration of the radially offset slot of FIG.21E.

FIG. 21G is another schematic illustration of the radially offset slotof FIG. 21E.

FIG. 21H is yet another schematic illustration of the radially offsetslot of FIG. 21E.

FIG. 22 is a cross-sectional view of an embodiment of a traction planetassembly that can be used with the variator subassembly of FIG. 16.

FIG. 23 is a perspective view of an embodiment of a housing member thatcan be used with the CVT of FIG. 2 or FIG. 15.

FIG. 24 is another perspective view of the housing member of FIG. 23.

FIG. 25 is a flow chart of a skew-based control process that can be usedwith the CVT of FIG. 2 or FIG. 15.

FIG. 26 is a chart representing a look-up table that can be used in asubprocess of the skew-based control process of FIG. 25.

FIG. 27 is a flow chart of an actuator subprocess that can be used withthe skew-based control process of FIG. 25.

FIG. 28A is a schematic illustration of an inventive embodiment of askew-based control system.

FIG. 28B is a schematic illustration of an inventive embodiment of askew actuator that can be used with the skew-based control system ofFIG. 28A.

FIG. 29A is a schematic illustration of certain electronic hardware thatcan be used with the skew-based control system of FIG. 28.

FIG. 29B is a flow chart of a skew-based control process that can beused with the CVT of FIG. 2 or FIG. 15.

FIG. 29C is another flow chart of a skew-based control process that canbe used with the CVT of FIG. 2 or FIG. 15.

FIG. 29D is yet another flow chart of a skew-based control process thatcan be used with the CVT of FIG. 2 or FIG. 15.

FIG. 30 is a perspective view of an inventive embodiment of acontinuously variable transmission (CVT) having a skew-based controlsystem.

FIG. 31 is a cross-sectional perspective view of the CVT of FIG. 30.

FIG. 32 is a cross-sectional view of the CVT of FIG. 30.

FIG. 33 is an exploded, cross-sectional, perspective view of the CVT ofFIG. 30.

FIG. 34 is a cross-section view of a variator subassembly that can beused with the CVT of FIG. 30.

FIG. 35 is an exploded, cross-sectional, perspective view of thevariator subassembly of FIG. 34.

FIG. 36 is an exploded, perspective view of an embodiment of a tractionplanet assembly that can be used with the variator subassembly of FIG.34.

FIG. 37 is a cross-sectional view of the traction planet assembly ofFIG. 36.

FIG. 38 is a perspective view of an inventive embodiment of a carrierinsert that can be used with the variator subassembly of FIG. 34.

FIG. 39 is a perspective view of a carrier member that can be used withthe variator subassembly of FIG. 34.

FIG. 40 is a cross-sectional perspective view of the carrier member ofFIG. 39.

FIG. 41 is a perspective view of an embodiment of a skew driver that canbe used with the CVT of FIG. 30.

FIG. 42 is a cross-sectional view B-B of the skew driver of FIG. 41.

FIG. 43 is a schematic illustration of an inventive embodiment of acontinuously variable transmission (CVT) having a skew-based controlsystem.

FIG. 44 is a schematic illustration of another inventive embodiment of acontinuously variable transmission (CVT) having a skew-based controlsystem.

FIG. 45 is a cross-sectional view of an embodiment of a variator.

FIG. 46 is a partial cross-sectional perspective view of a traction sunassembly that can be used in the variator of FIG. 45.

FIG. 47 is a cross-sectional view of the traction sun assembly of FIG.46.

FIG. 48 is a cross-sectional detail view C of the traction sun assemblyof FIG. 46.

FIG. 49 is a cross-section view of certain components of a variator thatcan be used with the CVT of FIG. 2, FIG. 15, and/or FIG. 30.

FIG. 50 is a cross-sectional view of another embodiment of carriermembers that can be used with the CVT of FIG. 2, FIG. 15, and/or FIG.30.

FIG. 51 is a cross-section view C-C of the carrier members of FIG. 50.

FIG. 52 is a cross-sectional view of one more embodiment of carriermembers that can be used with the CVT of FIG. 2, FIG. 15, and/or FIG.30.

DETAILED DESCRIPTION OF CERTAIN INVENTIVE EMBODIMENTS

The preferred embodiments will be described now with reference to theaccompanying figures, wherein like numerals refer to like elementsthroughout. The terminology used in the descriptions below is not to beinterpreted in any limited or restrictive manner simply because it isused in conjunction with detailed descriptions of certain specificembodiments of the invention. Furthermore, embodiments of the inventioncan include several novel features, no single one of which is solelyresponsible for its desirable attributes or which is essential topracticing the inventions described. Certain CVT embodiments describedhere are generally related to the type disclosed in U.S. Pat. Nos.6,241,636; 6,419,608; 6,689,012; 7,011,600; 7,166,052; U.S. patentapplication Ser. Nos. 11/243,484; 11/543,311; 12/198,402 and PatentCooperation Treaty patent applications PCT/US2007/023315,PCT/IB2006/054911, PCT/US2008/068929, and PCT/US2007/023315,PCT/US2008/074496. The entire disclosure of each of these patents andpatent applications is hereby incorporated herein by reference.

As used here, the terms “operationally connected,” “operationallycoupled”, “operationally linked”, “operably connected”, “operablycoupled”, “operably linked,” and like terms, refer to a relationship(mechanical, linkage, coupling, etc.) between elements whereby operationof one element results in a corresponding, following, or simultaneousoperation or actuation of a second element. It is noted that in usingsaid terms to describe inventive embodiments, specific structures ormechanisms that link or couple the elements are typically described.However, unless otherwise specifically stated, when one of said terms isused, the term indicates that the actual linkage or coupling may take avariety of forms, which in certain instances will be readily apparent toa person of ordinary skill in the relevant technology.

For description purposes, the term “axial” as used here refers to adirection or position along an axis that is parallel to a main orlongitudinal axis of a transmission or variator. The term “radial” isused here to indicate a direction or position that is perpendicularrelative to a longitudinal axis of a transmission or variator. Forclarity and conciseness, at times similar components labeled similarly(for example, bearing 152A and bearing 152B) will be referred tocollectively by a single label (for example, bearing 152).

It should be noted that reference herein to “traction” does not excludeapplications where the dominant or exclusive mode of power transfer isthrough “friction.” Without attempting to establish a categoricaldifference between traction and friction drives here, generally thesemay be understood as different regimes of power transfer. Tractiondrives usually involve the transfer of power between two elements byshear forces in a thin fluid layer trapped between the elements. Thefluids used in these applications usually exhibit traction coefficientsgreater than conventional mineral oils. The traction coefficient (μ)represents the maximum available traction forces which would beavailable at the interfaces of the contacting components and is ameasure of the maximum available drive torque. Typically, frictiondrives generally relate to transferring power between two elements byfrictional forces between the elements. For the purposes of thisdisclosure, it should be understood that the CVTs described here mayoperate in both tractive and frictional applications. For example, inthe embodiment where a CVT is used for a bicycle application, the CVTcan operate at times as a friction drive and at other times as atraction drive, depending on the torque and speed conditions presentduring operation.

Embodiments of the invention disclosed here are related to the controlof a variator and/or a CVT using generally spherical planets each havinga tiltable axis of rotation that can be adjusted to achieve a desiredratio of input speed to output speed during operation. In someembodiments, adjustment of said axis of rotation involves angulardisplacement of the planet axis in a first plane in order to achieve anangular adjustment of the planet axis in a second plane, wherein thesecond plane is substantially perpendicular to the first plane. Theangular displacement in the first plane is referred to here as “skew”,“skew angle”, and/or “skew condition”. For discussion purposes, thefirst plane is generally parallel to a longitudinal axis of the variatorand/or the CVT. The second plane can be generally perpendicular to thelongitudinal axis. In one embodiment, a control system coordinates theuse of a skew angle to generate forces between certain contactingcomponents in the variator that will tilt the planet axis of rotationsubstantially in the second plane. The tilting of the planet axis ofrotation adjusts the speed ratio of the variator. The aforementionedskew angle, or skew condition, can be applied in a plane substantiallyperpendicular to the plane of the page of FIG. 4, for example.Embodiments of transmissions employing certain inventive skew controlsystems for attaining a desired speed ratio of a variator will bediscussed.

One aspect of the torque/speed regulating devices disclosed here relatesto drive systems wherein a prime mover drives various driven devices.The prime mover can be, for example, an electrical motor and/or aninternal combustion engine. For purposes of description here, anaccessory includes any machine or device that can be powered by a primemover. For purposes of illustration and not limitation, said machine ordevice can be a power takeoff device (PTO), pump, compressor, generator,auxiliary electric motor, etc. Accessory devices configured to be drivenby a prime mover may also include alternators, water pumps, powersteering pumps, fuel pumps, oil pumps, air conditioning compressors,cooling fans, superchargers, turbochargers and any other device that istypically powered by an automobile engine. As previously stated,usually, the speed of a prime mover varies as the speed or powerrequirements change; however, in many cases the accessories operateoptimally at a given, substantially constant speed. Embodiments of thetorque/speed regulating devices disclosed here can be used to controlthe speed of the power delivered to the accessories powered by a primemover.

For example, in some embodiments, the speed regulators disclosed herecan be used to control the speed of automotive accessories driven by apulley attached to the crankshaft of an automotive engine. Usually,accessories must perform suitably both when the engine idles at lowspeed and when the engine runs at high speed. Often accessories operateoptimally at one speed and suffer from reduced efficiency at otherspeeds. Additionally, the accessory design is compromised by the need toperform over a large speed range rather than an optimized narrow speedrange. In many cases when the engine runs at a speed other than lowspeed, accessories consume excess power and, thereby, reduce vehiclefuel economy. The power drain caused by the accessories also reduces theengine's ability to power the vehicle, necessitating a larger engine insome cases.

In other situations, inventive embodiments of the torque/speedregulating devices disclosed here can be used to decrease or increasespeed and/or torque delivered to the accessories for achieving optimalsystem performance. In certain situations, inventive embodiments of thetorque/speed regulating devices disclosed here can be used to increasespeed to the accessories when the prime mover runs at low speed and todecrease speed to the accessories when the prime mover runs at highspeed. Thus, the design and operation of accessories can be optimized byallowing the accessories to operate at one, substantially favorablespeed, and the accessories need not be made larger than necessary toprovide sufficient performance at low speeds. The accessories can alsobe made smaller because the torque/speed regulating devices can reducespeed to the accessories when the prime mover runs at high speed,reducing the stress load the accessories must withstand at high rpm.Because the accessories are not subjected to high speeds, their expectedservice life can increase substantially. In some cases, smoother vehicleoperation results because the accessories do not have to run at low orhigh speed. Further, a vehicle can operate more quietly at high speedbecause the accessories run at a lower speed.

The torque/speed regulators disclosed here can facilitate reducing thesize and weight of the accessories as well as the prime mover, therebyreducing the weight of the vehicle and thus increasing fuel economy.Further, in some cases, the option to use smaller accessories and asmaller prime mover lowers the cost of these components and of thevehicle. Smaller accessories and a smaller prime mover can also provideflexibility in packaging and allow the size of the system to be reduced.Embodiments of the torque/speed regulators described here can alsoincrease fuel economy by allowing the accessories to operate at theirmost efficient speed across the prime mover operating range. Finally,the torque/speed regulators increase fuel economy by preventing theaccessories from consuming excess power at any speed other than low.

Referring now to FIGS. 1 and 2, in one embodiment a continuouslyvariable accessory drive (CVAD) 10 can include a continuously variabletransmission (CVT) 12 coupled to an alternator/generator 14. In oneembodiment, the alternator/generator 14 can be, as an illustrativeexample, a C. E. Niehoff 1224-3 alternator. In one embodiment, the CVT12 can be provided with a skew actuator 16 and a set of speed sensors 18that are configured to communicate with a skew-based control system (forexample, FIGS. 25-29). The CVT 12 can be provided with a lubricationmanifold 20 and a lubrication sump 22 that are adapted to couple to alubrication and cooling system (not shown). In one embodiment, a pulleycover 23 can be arranged between the CVT 12 and the alternator/generator14. The pulley cover 23 can provide structural attachment of the CVT 12to the alternator/generator 14, among other things. The pulley cover 23is adapted to radially surround a drive pulley 24. The drive pulley 24is configured to receive a power input, for example, from a belt (notshown). In some embodiments, the pulley cover 23 is adapted to provideaccess to the pulley for a belt.

Turning now to FIGS. 3-4, in one embodiment, the CVT 12 includes ahousing 26 adapted to couple to a housing cap 28. The housing 26 and thehousing cap 28 are configured to operably couple to, and substantiallyenclose, a variator subassembly 30. The variator subassembly 30 iscoupled to a first traction ring 32 and a second traction ring 34. Thefirst traction ring 32 is coupled to a first load cam roller assembly36. The second traction ring 34 can be coupled to a second load camroller assembly 38. In one embodiment, the first load cam rollerassembly 36 is coupled to an input cam driver 40. The second load camroller assembly 38 can be coupled to an output driver 42. In oneembodiment the input cam driver 40 is coupled to the drive pulley 24.Each of the load cam roller assemblies 36 and 38 can be provided with atoothed and/or notched outer periphery that can be arranged to be inproximity to each of the speed sensors 18. The variator subassembly 30can be operably coupled to the skew actuator 16 via a clevis 43.

In one embodiment, the CVT 12 can be provided with a main shaft 44 thatis substantially aligned with a longitudinal axis of the CVT 12. Themain shaft 44 can be provided with a keyed bore 45 that can be adaptedto receive, for example, a shaft of the alternator/generator 14. Thedrive pulley 24 can be radially supported on one end of the main shaft44 with a first bearing 46 and a second bearing 48. In some embodiments,a shim 50 can be placed between the bearings 46, 48. In one embodiment,the CVT 12 is provided with a thrust bearing 52 coupled to the mainshaft 44. The thrust bearing 52 can couple to the pulley 24. The thrustbearing 52 can be adapted to provide axial support for, and react axialforces from, certain components of the CVT 12. The first and secondbearings 46, 48 and the shim 50 can be configured to share a portion ofthe axial loads induced on the thrust bearing 52. The sharing of theaxial loads can extend the life of the thrust bearing 52 and can preventoverload of the thrust bearing 52, among other things.

In one embodiment, the variator subassembly 30 is provided with a numberof traction planet assemblies 54 arranged angularly about the main shaft44. The variator subassembly 30 can have a traction sun assembly 56arranged coaxial about the main shaft 44. The traction sun assembly 56can be configured to operably couple to each of the traction planetassemblies 54. The traction sun assembly 56 can be arranged radiallyinward of each of the traction planet assemblies 54. In someembodiments, the traction sun assembly 56 is adapted to move axiallyalong the main shaft 44. In one embodiment, the variator subassembly 30can include a first carrier member 58 operably coupled to a secondcarrier member 60. The first and second carrier members 58, 60 areadapted to support each of the traction planet assemblies 54. In oneembodiment, the first carrier member 58 can be coupled to a firstcarrier member cap 62. The second carrier member 60 can be coupled to asecond carrier member cap 64. The carrier member caps 62 and 64 can beconfigured to operably couple to the traction planet assemblies 54. Thecarrier member caps 62, 64 can be configured to react forces generatedduring the shifting of the CVT 12.

In some embodiments, the carrier member caps 62, 64 are integral withthe carrier members 58, 60, respectively. In other embodiments, thecarrier member caps 62, 64 are rigidly and permanently attached to thecarrier members 58, 60. In one embodiment, the carrier member caps 62,64 are separate components from the carrier members 58, 60 to enable theuse of different materials for the components. For example, the carriermember 58 can be made of aluminum while the carrier member cap 62 can bemade of steel. As a separate component, the carrier member cap 62 mayalso facilitate assembly of the traction planet assemblies 54 with thecarrier member 58. In some embodiments, configuring the carrier membercaps 62 as separate components can simplify the manufacture of the firstand second carrier members 58, 60.

Referring to FIG. 5, in one embodiment the variator subassembly 30includes a carrier retaining ring 66 that is adapted to couple to thefirst and second carrier members 58, 60. The carrier retaining ring 66can be coupled to the housing 26 and can be configured to besubstantially non-rotatable with respect to the longitudinal axis of theCVT 12. In one embodiment, each of the traction planet assemblies 54includes at least one leg 68 that is operably coupled to a planet axle70. Each of the legs 68 is adapted to operably couple to the tractionsun assembly 56. In one embodiment, the traction sun assembly 56includes a number of anti-rotation inserts 72. The anti-rotation inserts72 can be configured to substantially flank each of the legs 68. Theanti-rotation inserts 72 can be coupled to a first shift cam 74. In someembodiments, the anti-rotation inserts 72 can be coupled to a secondshift cam 76. In yet other embodiments, the anti-rotation inserts 72 canbe coupled to both the first and second shift cams 74 and 76. Theanti-rotation inserts 72 can substantially prevent the shift cams 74 and76 from rotating during operation of the CVT 12.

During operation of the CVT 12, a power input can be coupled to thedrive pulley 24 with, for example, a belt or chain (not shown). Thedrive pulley 24 transfers the power input to the input cam driver 40,which transfers power to the first traction ring 32 via the first loadcam roller assembly 36. The first traction ring 32 transfers the powerto each of the traction planet assemblies 54. Each of the tractionplanet assemblies 54 delivers power to the second traction ring 34 whichtransfers power to the output cam driver 42 via the second load camroller assembly 38. In one embodiment, the output driver 42 deliverspower to the main shaft 44. The main shaft 44 can be coupled to, forexample, the alternator/generator 14 via the keyed bore 45. A shift inthe ratio of input speed to output speed, and consequently a shift inthe ratio of input torque to output torque, is accomplished by tiltingthe rotational axis of the traction planet assemblies 54 to a tilt anglesometime referred to here as gamma (γ). The tilting of the rotationalaxis of the traction planet assemblies 54 occurs in substantially in theplane of the page of FIG. 4, for example. The tilting of the rotationalaxis of the traction planet assemblies 54 can be accomplished byrotating the second carrier member 60 with respect to the first carriermember 58 about the longitudinal axis. This relative angular rotationaldisplacement is sometimes referred to here as β. The rotation of thesecond carrier member 60 with respect to the first carrier member 58induces a skew angle, a condition sometimes referred to here as a “skewcondition”, on each of the traction planet assemblies 54. The skew anglecan be applied in a plane that is substantially parallel to thelongitudinal axis of the CVT 12 (for example, a plane perpendicular tothe plane of the page of FIG. 4). In one embodiment, the skew angle canbe in the range of 0 degrees to 15 degrees. Typically the skew angle isin the range of 0 degrees to 8 degrees.

Turning now to FIG. 6, in one embodiment the input cam driver 40 iscoupled to the drive pulley 24. The input cam driver 40 can be providedwith a number of roller reaction surfaces 78 that can be adapted tooperably couple to the first load cam roller assembly 36. The main shaft44 can be provided with a central lubricant passage 80 that feeds anumber of lubricant distribution passages 82A, 82B, 82C. The lubricantdistribution passages 82A, 82B, 82C intersect the central lubricantpassage 80 and extend radially outward from the center of the main shaft44. In one embodiment, the main shaft 44 can be provided with a splinedportion 84 that is configured to couple to the output cam driver 42. Themain shaft 44 can be provided with a shoulder 86 in proximity to one endof the splined portion 84. The main shaft 44 can be provided with agroove 88 on an opposite end of the spline portion 84. In someembodiments, the main shaft is provided with a threaded bore 90 on oneend. During assembly of the CVT 12, the variator subassembly 30 isarranged coaxially with the main axle 44. An assembly tool (not shown)is coupled to the threaded bore 90. The assembly tool threads into thebore 90 and applies force on the output ring 42 to facilitate theclamping of the output ring 42 and the input ring 40 to a predeterminedaxial force. At least one clip 92 (FIGS. 3 and 4) can be placed in thegroove 88 to retain the axial preload setting once the assembly tool isremoved. In some embodiments, shims (not shown) can be placed in thegroove 88 with the clip 92 to retain the axial preload setting.

Passing now to FIG. 7, in one embodiment the first carrier member 58 isadapted to couple to the second carrier member 60 via a shoulder bolt94. The shoulder bolt 94 can be configured to couple to the carrierretaining ring 66. In one embodiment, a shim 96 can be placed under thehead of the shoulder bolt 94. The thickness of the shim 96 can beselected to adjust the axial force and/or the axial gap between thefirst carrier member 58 and the second carrier member 60 upon tighteningof the shoulder bolt 94. In one embodiment, it is desirable to haveminimal axial force between the first carrier member 58 and the secondcarrier member 60 so that the second carrier member 60 can rotate withrespect to the first carrier member 58 about the longitudinal axis whilehaving minimal axial displacement or play between the first carriermember 58 and the second carrier member 60. In some embodiments, thecarrier retaining ring 66 is coupled to the housing 26 and issubstantially non-rotatable about the longitudinal axis. In otherembodiments, a thrust bearing (not shown) can be provided between thefirst and second carrier members 58 and 60.

Referring now to FIG. 8, in one embodiment the carrier retaining ring 66is a substantially annular ring having a reaction face 98 formed on aninner circumference. The carrier retaining ring 66 can be provided witha flange 100 located on an outer circumference of the substantiallyannular ring. The flange 100 can be configured to couple to, forexample, the housing 26. In one embodiment, the carrier retaining ring66 is provided with an opening 102 placed substantially between thereaction face 98 and the flange 100. In some embodiments, the reactionface 98 is formed with a number of fastening holes 104 that are adaptedto receive the shoulder bolts 94. The flange 100 can be provided with afastening hole 106 that can be configured to secure the carrierretaining ring 66 to the housing 24.

Passing now to FIG. 9, in one embodiment the clevis 43 can be providedwith at least one fork 110. The fork 110 extends from a base 112. Thebase 112 can be provided with a set screw land 114. The clevis 43 can becoupled to the carrier member 58 or to the second carrier member 60. Inone embodiment, the base 112 is attached to one of the first or secondcarrier members 58, 60 with, for example, a set screw (not shown). Thefork 110 can be arranged to extend through the opening 102. Duringoperation of the CVT 12 and the actuator 16 can be coupled to the fork110 to facilitate a change in ratio of the CVT 12. In one embodiment,the change in ratio of the CVT 12 is accomplished by rotating the secondcarrier member 60 with respect to the first carrier member 58. In someembodiments, the change in ratio of the CVT 12 is accomplished byrotating the first carrier member 58 with respect to the second carriermember 60.

Turning now to FIG. 10, in one embodiment, the carrier member 58 can bea substantially bowl-shaped body having a flange 120. A number ofsupport fingers 122 can extend radially inward from the flange 120 tothereby form a cavity of the bowl-shaped body. Each finger 122 isflanked on each side by a reaction surface 124. Each finger can also beprovided with a fastening hole 126. The fastening hole 126 canfacilitate the coupling of the first carrier member cap 62 to thecarrier member 58. In one embodiment, the flange 120 included a numberof holes 128 and slots 130. In some embodiments, the holes 128 and theslots 130 can be arranged about the flange 120 so that each hole 128 isflanked by the slots 130 and vice versa. In one embodiment, the carriermember 58 and the carrier member 60 are substantially similar. Onceassembled the holes 128 on the carrier member 58 can align with theslots 130 of the carrier member 60 and vice versa. The flange 120 can beprovided with a notch 132. The notch 132 can be adapted to couple to theclevis 43. The flange 120 can be provided with a set screw hole 134arranged to intersect the notch 132 and the outer periphery of theflange 120. The set screw hole 134 can facilitate the coupling of theclevis 43 to the carrier member 58 with, for example, a set screw (notshown). The carrier member 58 can have a number of clearance openings140. In one embodiment, the clearance openings 140 are configured tocooperate with each of the traction planet assemblies 54.

Referring now to FIGS. 11-12B, in one embodiment the traction planetassembly 54 includes a substantially spherical traction planet 150having a central bore. The traction planet 150 can be operably coupledto the planet axle 70 with bearings 152. In some embodiments, a spacer154 can be operably coupled to the planet axle 70 and located betweenthe bearings 152. The planet axle 70 can be coupled on each end to thelegs 68. A skew reaction roller 156 can be operably coupled to each ofthe planet axle 70. A shift reaction ball 158 can be pressed into a bore160 formed on each end of the planet axle 70. A shift cam roller 162 canbe operably coupled to each leg 68. The shift cam roller 162 can becoupled to a shift cam roller axle 164. The shift cam roller axle 164can be coupled to a shift cam roller axle bore 166 formed on the leg 68.The shift cam roller 162 can be positioned in a slot 168 formed on oneend of the leg 68. In one embodiment, the slot 168 is substantiallyperpendicular to the shift cam roller axle bore 166. The leg 68 can beprovided with a planet axle bore 170. The planet axle bore 170 can beformed on the leg 68 at an end opposite that of the slot 166. The leg 68can be provided with a skew reaction roller clearance shoulder 172. Theleg 68 can have a side 174 that has an angular taper when viewed in theplane of the page of FIG. 12B. In one embodiment, the side 174 has anangle 176 with respect to vertical in the range of about 5 degrees to 10degrees.

Turning now to FIGS. 13 and 14, in one embodiment the traction sunassembly 56 includes a traction sun 180 that is operably coupled to thefirst and second shift cams 74 and 76. The shift cams 74 and 76 can bearranged to substantially flank the traction sun 180. In one embodiment,the shift cams 74 and 76 are substantially similar. The traction sunassembly 56 can include a set of bearings 184. Each bearing 184 can becoupled to a bearing race 186. The bearing race 186 is configured tocouple to a shoulder 188 formed on an inner diameter of the traction sun180. In one embodiment, the bearing races 186 are coupled to a spring190. The spring 190 can facilitate the axial preload of the bearingraces 186 thereby applying an axial preload force to the bearings 184and the shift cams 74 and 76. The traction sun assembly 56 can beprovided with bearings 192. The bearings 192 can be adapted tofacilitate the coupling of the traction sun assembly 56 to the mainshaft 44. In one embodiment, the traction sun assembly includes a numberof anti-rotation spacers 194. Each anti-rotation spacer 194 can becoupled to the shift cams 182. In one embodiment, the shift cams 74 and76 are provided with a number of seats 196 configured to couple to theanti-rotation spacers 194. Each anti-rotation spacer 194 is providedwith a hole 198. Each seat 196 is provided with a hole 200. The holes198 and 200 are adapted to facilitate the coupling of the anti-rotationinserts 194 to the shift cam 74. In one embodiment, the shift cam 74 canbe a generally disc-shaped body having a shoulder 202 extending from oneend. A bearing race 204 can be formed on the shoulder 202. The bearingrace 204 can be adapted to couple to the bearing 184. In someembodiments, the shift cam 74 can be provided with a cam surface 206.The cam surface 206 can have a substantially curved profile when viewedin cross-section in the plane of FIG. 14.

Passing now to FIG. 15, in one embodiment a CVT 1000 can include ahousing 1002 coupled to a housing cap 1004. The housing 1002 and thehousing cap 1004 can be configured to operably couple to, andsubstantially enclose, a variator subassembly 1006. The variatorsubassembly 1006 can be coupled to a first traction ring 1008 and asecond traction ring 1010. The first traction ring 1008 can be coupledto a first load cam roller assembly 1012. The second traction ring 1010can be coupled to a second load cam roller assembly 1014. In oneembodiment, the first load cam roller assembly 1012 is coupled to aninput cam driver 1016. The second load cam roller assembly 1014 can becoupled to an output driver 1018. In one embodiment, the input camdriver 1016 can be coupled to the drive pulley 24. Each of the load camroller assemblies 1012 and 1014 can be provided with a toothed and/ornotched outer periphery that can be configured to be in proximity toeach of the speed sensors 18. The variator subassembly 1006 can beoperably coupled to the skew actuator 16 with the clevis 43 (FIG. 3). Inone embodiment, the CVT 1000 can be provided with a main shaft 1020 thatis substantially aligned with a longitudinal axis 1022 of the CVT 1000.The main shaft 1020 can be provided with a keyed bore 1025 that can beadapted to receive, for example, a shaft of the alternator/generator 14,or any other accessory device. The drive pulley 24 can be operablycoupled to the main shaft 1020. In one embodiment, the coupling of thedrive pulley 24 to the main shaft 1020 is substantially similar to thecoupling of the drive pulley 24 to the main shaft 44.

Referring to FIGS. 15-18, in one embodiment, the variator subassembly1006 can include a number of traction planet assemblies 1024 arrangedangularly about the longitudinal axis 1022. The variator subassembly1006 can include a traction sun assembly 1026 arranged coaxial about themain shaft 1020. The traction sun assembly 1026 can be located radiallyinward of each of the traction planet assemblies 1024. In oneembodiment, the traction sun assembly 1026 can be adapted to besubstantially axially fixed along the main shaft 1020. In oneembodiment, the variator subassembly 1006 can include a first carriermember 1028 operably coupled to a second carrier member 1030. The firstand second carrier members 1028, 1030 are configured to support each ofthe traction planet assemblies 1024.

In one embodiment, the first carrier member 1028 is coupled to a firstcarrier member cap 1032. The second carrier member 1030 can be coupledto a second carrier member cap 1034. The carrier member caps 1032, 1034are adapted to operably couple to the traction planet assemblies 1024.In one embodiment, the variator subassembly 1006 can include a carrierretaining ring 1036. The carrier retaining ring 1036 can be configuredto couple to the first and second carrier members 1028, 1030. Thecarrier retaining ring 1036 can be provided with a flange 1038. Theflange 1038 can be coupled to the housing 1002 and can be configured tobe substantially non-rotatable with respect to the longitudinal axis1022. The carrier retaining ring 1036 can be provided with an opening1040 through which the clevis 43 can be placed to couple to, forexample, the second carrier member 1030. A number of shoulder bolts 1042can be provided to operably couple the first and second carrier members1028, 1030 to the carrier retaining ring 1036. The coupling of the firstand second carrier members 1028, 1030 to the carrier retaining ring 1036can be configured in a substantially similar manner as the coupling ofthe first and second carrier members 58, 60 to the carrier retainingring 66 (FIG. 7).

During operation of the CVT 1000, a power input can be coupled to thedrive pulley 24 with, for example, a belt or chain (not shown). Thedrive pulley 24 can transfer the power input to the input cam driver1016. The input cam driver 1016 can transfer power to the first tractionring 1008 via the first load cam roller assembly 1012. The firsttraction ring 1008 transfers the power to each of the traction planetassemblies 1024. Each of the traction planet assemblies 1024 deliverspower to the second traction ring 1010. The second traction ring 1010delivers power to the output driver 1018. The output driver 1018 isconfigured to deliver power to the main shaft 1020 so that power can betransferred out of the CVT 1000. A shift in the ratio of the input speedto the output speed, and consequently a shift in the ratio of the inputtorque to the output torque can be accomplished by tilting therotational axis of the traction planet assemblies 1024 to a tilt angle(γ). The tilting of the rotational axis of the traction planetassemblies 1024 can be facilitated by rotating the first carrier member1028 with respect to the second carrier member 1030. The rotation of thefirst carrier member 1028 with respect to the second carrier member 1030generates a skew condition of the type generally described in U.S.patent application Ser. No. 12/198,402 filed on Aug. 26, 2008, theentire disclosure of which is hereby incorporated herein by reference. Askew condition can be applied to the traction planet assemblies 1024 bytwo events, occurring separately or in combination. One event is achange in the angular rotation (β) of the carrier member 1028, and theother event is a change in the tilt angle (γ) of the traction planetassemblies 1024. For a constant angular rotation (β) of the carriermember 1028, the skew condition can approach a zero skew-angle conditionas the rotational axis of the traction planet assemblies 1024 tilts. Therotational axis of the traction planet assemblies 1024 can stop tiltingwhen a zero skew-condition is reached. The zero-skew condition is anequilibrium condition for the tilt angle (γ).

Referring still to FIGS. 15-18, in one embodiment the traction sunassembly 1026 can include a traction sun 1044 operably coupled to firstand second traction sun supports 1046 with bearings, for example. Thetraction sun supports 1046 can be adapted to contact the first andsecond carrier members 1028, 1030. The first and second carrier members1028, 1030 can constrain and/or limit axial motion of the traction sunassembly 1044. In one embodiment, the traction sun supports 1046 can becoupled to wave springs (not shown) positioned between the traction sunsupports 1046 and the first and second carrier members 1028, 1030. Thewave springs can energize during operation of the CVT 1000 to provide aminimum axial travel to the traction sun assembly 1026. In someembodiments, the traction sun supports 1046 are coupled to the first andsecond carrier members 1028 and 1030 via a screw lead (not shown) sothat a rotation of either the first or second carrier members 1029, 1030tends to axially displace the traction sun assembly 1026. In otherembodiments, an actuator (not shown) can be coupled to the traction sunassembly 1026 to facilitate a change in the axial position of thetraction sun assembly 1026 based at least in part on the tilt angle (γ)of the traction planet assemblies 1024 of the CVT 1000. In yet otherembodiments, an actuator (not shown) can be coupled to the traction sunassembly 1026 to facilitate a change in the axial position of thetraction sun assembly 1026 that is substantially random with respect tothe tilt angle (γ) of the traction planet assemblies 1024. Theaforementioned methods of axially positioning the traction sun assembly1026 can increase the expected life of the traction sun 1044, forexample, by distributing operational loads over a larger area of thesurface of the traction sun 1044 than would otherwise be achievable.

Turning now to FIG. 19-21C, in one embodiment the first carrier member1028 can be provided with a number of radially offset slots 1050. Thesecond carrier member 1030 can be provided with a number of radial slots1052. The radial slots 1052 are shown in dashed lines in FIG. 19. Theradially offset slots 1050 and the radial slots 1052 are sized toaccommodate certain components of the traction planet assemblies 1024,for example a skew reaction roller 1100 (FIG. 22). For discussionpurposes, the arrangement of the radially offset slots 1050 with respectto the radial slots 1052 can be shown as projections in a planeperpendicular to the longitudinal axis 1022. The longitudinal axis 1022is perpendicular to the plane of the page of FIG. 19. A radialconstruction line 1054 can be shown perpendicular to the longitudinalaxis 1022. The construction line 1054 radially passes through a center1056 of the first and second carrier members 1028, 1030. Likewise, asecond construction line 1058 can pass through the center 1056. Theconstruction line 1058 substantially bisects the radial slots 1052. Aradially offset construction line 1060 is parallel to the constructionline 1054. The radially offset construction line 1060 is perpendicularto the longitudinal axis 1022. An offset distance 1062 separates theradially offset construction line 1060 from the construction line 1054.In one embodiment, the offset distance 1062 is in the range of about 5mm to 20 mm. In some embodiments, the offset distance 1062 is between16-18 mm. In some embodiments, the offset distance 1062 is proportionalto the width of the radially offset slot 1050. For example, the offsetdistance 1062 can be about equal to the width of the radially offsetslot 1050. The radially offset construction line 1060 substantiallybisects the radially offset slot 1050. The radially offset constructionline 1060 intersects the second construction line 1058 to thereby forman angle 1064 (sometimes referred to here as ψ). In one embodiment, theangle (ψ) 1064 can be in the range of 5 degrees to 45 degrees forconditions where the traction planet subassemblies 1024 are at a tiltangle (γ) substantially equal to zero. Preferably, the angle (ψ) 1064 isin the range of 10 degrees to 20 degrees when the traction planetsubassemblies 1024 are at a tilt angle (γ) substantially equal to zero.

Referring still to FIG. 19, in one embodiment the first carrier member1028 can be provided with a number of clearance openings 1066. Thesecond carrier member 1030 can be provided with a number of clearanceopenings 1068. The clearance openings 1066, 1068 can be adapted toprovide clearance to each of the traction planet assemblies 1024. In oneembodiment, the clearance opening 1066 is larger than the clearanceopening 1068 to provide additional clearance to the traction planetassembly 1024 during operation of the CVT 1000.

Referring now to FIGS. 20A-20C, in one embodiment the first carriermember 1028 can be a substantially bowl-shaped body having a centralbore 1070 and a flange 1072 about the outer periphery of the bowl-shapedbody. The flange 1072 can be provided with a number of holes 1074 and anumber of slots 1076. The holes 1074 and the slots 1076 can be adaptedto facilitate the coupling of the first carrier member 1028 to thesecond carrier member 1030 with, for example, the shoulder bolts 1042,in such a manner as to allow relative rotational displacement betweenthe carrier members 1028, 1030 while providing axial constraint. Thefirst carrier member 1028 can be provided with a reaction shoulder 1078arranged about the central bore 1070. In one embodiment, the reactionshoulder 1078 can be configured to contact the traction sun support1046. The flange 1072 can be provided with a notch 1080. The notch 1080can be adapted to facilitate the coupling of the first carrier member1028 to the clevis 43. The first carrier member 1028 can be providedwith a number of holes 1082 located on a bottom face of the bowl-shapedbody. The holes 1082 can be arranged to facilitate the coupling of thefirst carrier member cap 1032 to the first carrier member 1028. In oneembodiment, each radial slot 1050 is provided with a reaction surface1084. The reaction surfaces 1084 are configured to facilitate thecoupling of the first carrier member 1028 to the traction planetassemblies 1024.

Referring to FIGS. 21A-21D, the construction line 1058 can form theangle (ψ) 1064 with the offset construction line 1060. During operationof the CVT 1000, the carrier members 1028, 1030 can be rotated about thelongitudinal axis 1022. The offset construction line 1060 follows thefirst carrier member 1028 and the construction line 1058 follows thesecond carrier member 1030. For clarity, the construction lines 1058 and1060 are depicted in FIGS. 21B-21D for three angular rotationalpositions about the longitudinal axis of, for example, the secondcarrier member 1030 with respect to the first carrier member 1028 (thisrelative angular rotational position is sometimes referred to here asβ). As the carrier members 1028, 1030 are rotated relative to eachother, the angle (ψ) 1064 can change and an intersection location 1063can move radially relative to the construction line 1058. For example,an angle 10640 depicted in FIG. 21B is smaller than an angle 10641depicted in FIG. 21D. The angle 10640 is formed between the constructionline 1058 and the construction line 1060 when then tilt angle (γ) isless than zero. The angle 10641 is formed between the construction line1058 and the construction line 1060 when the tilt angle (γ) is greaterthan zero. In some embodiments, location of the carrier members 1028,1030 may be reversed in the CVT 1000. Such a reversal may alter therelationship embodied in FIG. 21. The intersection location 1063 can beshown at the intersection between the offset construction line 1060 andthe construction line 1058. The intersection location 1063 generallycorresponds to a skew angle equal to zero, or a “zero-skew condition”,for the traction planet subassemblies 1024 at a constant tilt angle (γ).The amount of change of the angle (ψ) 1064 is sometimes an indication ofthe stability of the tilt angle (γ) of the traction planet assemblies1024 during operation. A high value for the angle (ψ) 1064 tends to bemore stable and exhibit slower shifting than a low angle that tends tobe less stable and exhibits faster shifting.

Referring specifically now to FIG. 21E-21H, in one embodiment a radiallyoffset slot 1051 can have a curved profile that generally follows aconstruction line 1059. In some embodiments, the carrier member 1028 canbe provided with the radially offset slots 1051. The curvature of theconstruction line 1059, and consequently the curvature of the radiallyoffset slot 1051, can be configured to provide the desired controlstability and response of the CVT 1000. For illustrative purposes, aconstruction line 1061 can be shown tangent to the construction line1059 at an intersection location 1065. The intersection location 1065 isgenerally at the intersection between the construction line 1058 and theconstruction line 1059. The angle (ψ) 1064 is shown in FIG. 21E betweenthe construction line 1058 and the construction line 1061. In someembodiments, the curvature of the construction line 1059 can be arrangedto provide a constant angle (ψ) 1064 between the construction lines 1058and 1061 as the carrier member 1028 is rotated relative to carriermember 1030 by the angle β about the longitudinal axis. For clarity, theconstruction lines 1058, 1059, and 1061 are depicted in FIGS. 21F-21Hfor three angular rotational positions (β). As the carrier members 1028,1030 are rotated relative to each other, the angle (ψ) 1064 remainsconstant and the intersection location 1065 can move radially relativeto the construction line 1058. In some embodiments, the angle (ψ) 1064may vary arbitrarily between the tilt angle (γ) conditions depicted fromFIG. 21F through FIG. 21H. The variation on the construction angle 1064may be chosen to optimize control conditions of the CVT 1000. Theresulting path of the construction line 1059 can be formulated usingtechniques available to those skilled in the relevant technology.

Turning now to FIG. 22, in one embodiment the traction planet assembly1024 includes a substantially spherical planet 1090 having a centralbore. The planet 1090 can be operably coupled to a planet axle 1092with, for example, bearings 1094. In one embodiment, a spacer 1096 canbe placed between the bearings 1094. In some embodiments, the spacer1096 is integral with the bearings 1094. The bearings 1094 can beretained on the planet axle 1092 with rings 1098. In some embodiments,the rings 1098 can be integral with the bearing 1094. In one embodiment,the traction planet assembly 1024 can include a skew reaction roller1100 coupled to each end of the planet axle 1092. The skew reactionroller 1100 can be retained on the planet axle 1092 with a collar 1101.In one embodiment, the collar 1101 can be attached to the planet axle1092 with a press fit or other suitable means of attachment. In otherembodiments, the collar 1101 can be restrained by the carrier caps 1032and 1034 (FIG. 15). Each end of the planet axle 1092 can be adapted toreceive a shift reaction ball 1102. In one embodiment, the shiftreaction ball 1102 is pressed into a hole 1103 formed on each end of theplanet axle 1092. In some embodiments, the shift reaction ball 1102 cancontact the first carrier member cap 1032 or the second carrier membercap 1034 during operation of the CVT 1000.

Passing now to FIGS. 23 and 24, in one embodiment the housing 1002 canbe a substantially bowl-shaped body 1109 having a flange 1110 formed ona first end and a lubricant supply hub 1112 formed on a second end. Theflange 1110 can be configured to couple to a support structure, forexample, the pulley cover 23. The lubricant supply hub 1112 can beprovided with a lubricant passage 1113. The lubricant passage 1113 canbe adapted to couple to an external pump (not shown). The housing 1002can be provided with a sensor mounting hub 1114 located on the outerperiphery of the bowl-shaped body 1009. The sensor mounting hub 1114 canfacilitate the mounting of, for example, the speed sensors 18. The speedsensor 18 can be inserted into an access bore 1115 to facilitate theplacement of the speed sensor 18 in proximity to the load cam rollerassembly 1012. In one embodiment, the housing 1002 can include alubricant reservoir 1116 attached to the outer periphery of thebowl-shaped body 1009 at a mounting interface 1117. The lubricantreservoir 1116 can be provided with a number of fins 1118. The fins 1118can facilitate the transfer of heat from a lubricant to the ambient airduring operation of, for example, the CVT 12. The lubricant reservoir1116 can also be provided with a lubricant passage 1119. In someembodiments, the lubricant passage 1119 is adapted to couple to anexternal pump (not shown). In one embodiment, the housing 1002 can beprovided with an actuator mounting hub 1120 located on the outerperiphery of the bowl-shaped body 1009. The actuator mounting hub 1120can be configured to attach to, for example, the actuator 16. Theactuator mounting hub can be adapted to facilitate the coupling of theactuator 16 to, for example, the clevis 43.

Referring now to FIG. 25, in one embodiment a skew-based control process2000 can be implemented on, for example, a microprocessor incommunication with power electronics hardware of the CVT 1000. In someembodiments, the skew-based control process 2000 can be implemented on amicroprocessor in communication with the CVT 12 or other CVT embodimentsdescribed herein. The skew-based control process 2000 begins at a block2002. The skew-based control process 2000 then proceeds to a block 2004where a desired speed ratio (SR) set point of the CVT 1000 is received.In one embodiment the desired SR set point is received from a user. Insome embodiments, the desired SR setpoint is received from predeterminedmap residing in memory of a controller (for example, see FIG. 28A). Theskew-based control process 2000 continues to a block 2006 where anangular rotation about the longitudinal axis of, for example, the secondcarrier member 1030 with respect to the first carrier member 1028 (β) isdetermined. Next, the skew-based control process 2000 moves to anactuator subprocess 2008 where the angular rotation (β) is applied tothe carrier member 1028, for example. Upon completion of the actuatorsubprocess 2008, the skew-based control process 2000 proceeds to a block2009 where the actual SR of the CVT 1000 is measured. In one embodiment,the actual SR of the CVT 1000 can be determined by measuring the speedof, for example, the load cam roller assemblies 1012 and 1014, or anyother component indicative of input speed and output speed to the CVT1000. In some embodiments, the actual SR can be calculated based atleast in part on a target output speed condition or based at least inpart on a target input speed condition. In other embodiments, the actualSR of the CVT 1000 can be determined by measuring the tilt angle (γ) ofthe planet axle 1092. In yet other embodiments, the actual SR of the CVT1000 can be determined by measuring an actual torque ratio of the CVT1000. The actual torque ratio of the CVT 1000 can be determined bymeasuring the torque of, for example the traction rings 1008 and 1010,or any other component indicative of input torque and output torque tothe CVT 1000. In some embodiments, the torque indicative of input torqueand output torque can be determined by measuring the torque reacted onthe first carrier member 1028 and the second carrier member 1030,respectively. Next, the skew-based control process 2000 proceeds to adecision block 2010 where the measured speed ratio is compared to thedesired speed ratio set point to thereby form a comparison value. If themeasured speed ratio is not equal to the desired speed ratio set point,the skew-based control process 2000 returns to the block 2006. If themeasured speed ratio is equal to the desired speed ratio set point, theskew-based control process 2000 proceeds to an end block 2012. Theskew-based control process 2000 remains at the end block 2012 until anew speed ratio set point is received. In some embodiments, theskew-based control process 2000 is configured to operate in an open loopmanner; in such a case, the blocks 2009 and 2010 are not included in theskew-based control process 2000.

Referring to FIG. 26, in one embodiment the block 2006 can use a look-uptable that can be represented by a curve 2007. The curve 2007 depicts anexemplary relationship between the angular rotation (β) and the desiredspeed ratio of, for example, the CVT 1000. The block 2006 can use thecurve 2007 during open loop operation of the skew-based control process2000. The curve 2007 can be expressed by the equation y=Ax²−Bx+C, wherey is the angular rotation (β) and x is the speed ratio. In oneembodiment, the values of A, B, and C are 0.5962, 4.1645, and 3.536,respectively. In some embodiments, the values of A, B, and C are 0.5304,4.0838, and 3.507, respectively. In other embodiments, the values of A,B, and C are related to the dimensions and geometry of the CVT 1000, forexample, the position of slot 1050 and 1052 on the carrier members 1028and 1030, the length of the planet axle 1092, and dimensions of thetraction rings 1008 and 1010, among other things. In one embodiment, theblock 2006 can be configured to include a well-known PID control processappropriate for closed-loop operation of the skew-based control system2000. In the closed-loop configuration, the block 2006 determines theangular rotation (β) based at least in part on the comparison (sometimesreferred to here as error) between the actual SR and the SR setpoint.

Referring to FIG. 27, in one embodiment the actuator subprocess 2008 canbegin at a block 2014 and proceed to a block 2015 where a set point forthe angular rotation (β) is received. The actuator subprocess 2008proceeds to a block 2016 where an actuator command signal is determinedbased at least in part on the angular rotation (β). In one embodiment, alook-up table can be used to convert the angular rotation (β) set pointto an actuator command signal. In some embodiments, the actuator commandsignal can be a voltage or a current. In other embodiments, the actuatorcommand signal can be a change in the position of a cable or a linkage.In some embodiments, an algorithm can be used to derive the actuatorcommand signal from the angular rotation (β) set point. Next, theactuator subprocess 2008 proceeds to a block 2017 where the actuatorcommand signal is sent to an actuator and associated hardware. In oneembodiment, a standard serial communication protocol can be used to sendthe command signal to the actuator hardware. In some embodiments, acable or a linkage can be used to transmit the command signal to theactuator hardware. The actuator subprocess 2008 then passes to a block2018 where the carrier member, for example the carrier member 1028, isrotated. Next, the actuator subprocess 2008 passes to a block 2019 wherethe angular rotation (β) is measured. The actuator subprocess 2008 thenproceeds to a decision block 2020 where the measured angular rotation(β) is compared to the set point for the angular rotation (β). If themeasured angular rotation (β) is not equal to the angular rotation (β)set point, the actuator subprocess 2008 returns to the block 2016. Ifthe measured angular rotation (β) is equal to the angular rotation (β)set point, the actuator subprocess 2008 then ends at a block 2022,wherein the skew-based control process 2000 can continue at block 2009as described above with reference to FIG. 25. In some embodiments, theactuator subprocess 2008 is configured to operate in an open loopmanner; in such a case, the blocks 2019 and 2020 are not included in thesubprocess 2008.

Passing now to FIG. 28A, in one embodiment a control system 2050 can beconfigured to control a CVT 2051 coupled to a prime mover 2052 and aload 2053. The CVT 2051 can be configured to accommodate a skew-basedcontrol system. In some embodiments, the CVT 2051 is substantiallysimilar to the CVT 12 and/or the CVT 1000. The CVT 2051 can be coupledto a skew actuator 2054. In one embodiment, the skew actuator 2054 canbe substantially similar to, for example, the skew actuator 16. In someembodiments, the skew actuator 2054 is a servo actuator. In otherembodiments, the skew actuator 2054 can be a mechanical lever (notshown). In yet other embodiments, the skew actuator 2054 can be ahydraulic actuator or an electro-hydraulic actuator (not shown). Thecontrol system 2050 can include a number of sensors 2055 in electricaland/or mechanical communication with the CVT 2051, a control module2056, and a skew control module 2057. In some embodiments, the sensors2055 can be in communication with the prime mover 2052, the load 2053,and/or the actuator 2054. The sensors 2055 are in communication with thecontrol module 2056. In one embodiment, the control module 2056 is incommunication with the skew actuator 2054. The control module 2056 canbe configured to communicate with the skew control module 2057. In oneembodiment, the skew control module 2057 is configured to perform theskew-based control process 2000. In some embodiments, the control module2056 is in communication with a data display module 2058 configured toprovide a user control interface using one or more displays and/or inputdevices (not shown).

Those of skill will recognize that the various illustrative logicalblocks, modules, circuits, and algorithm steps described in connectionwith the embodiments disclosed herein, including with reference to thecontrol system 2050 may be implemented as electronic hardware, softwarestored on a computer readable medium and executable by a processor, orcombinations of both. To clearly illustrate this interchangeability ofhardware and software, various illustrative components, blocks, modules,circuits, and steps have been described above generally in terms oftheir functionality. Whether such functionality is implemented ashardware or software depends upon the particular application and designconstraints imposed on the overall system. Skilled artisans mayimplement the described functionality in varying ways for eachparticular application, but such implementation decisions should not beinterpreted as causing a departure from the scope of the presentinvention. For example, various illustrative logical blocks, modules,and circuits described in connection with the embodiments disclosedherein may be implemented or performed with a general purpose processor,a digital signal processor (DSP), an application specific integratedcircuit (ASIC), a field programmable gate array (FPGA) or otherprogrammable logic device, discrete gate or transistor logic, discretehardware components, or any combination thereof designed to perform thefunctions described herein. A general purpose processor may be amicroprocessor, but in the alternative, the processor may be anyconventional processor, controller, microcontroller, or state machine. Aprocessor may also be implemented as a combination of computing devices,e.g., a combination of a DSP and a microprocessor, a plurality ofmicroprocessors, one or more microprocessors in conjunction with a DSPcore, or any other such configuration. Software associated with suchmodules may reside in RAM memory, flash memory, ROM memory, EPROMmemory, EEPROM memory, registers, a hard disk, a removable disk, aCD-ROM, or any other suitable form of storage medium known in the art.An exemplary storage medium is coupled to the processor such theprocessor can read information from, and write information to, thestorage medium. In the alternative, the storage medium may be integralto the processor. The processor and the storage medium may reside in anASIC. For example, in one embodiment, the control module 2056 comprisesa processor (not shown). The processor of the control module 2056 mayalso be configured to perform the functions described herein withreference to one or both of the skew control module 2057 and the datadisplay module 2058.

Turning to FIG. 28B, in one embodiment the skew actuator 2054 caninclude a hydraulic piston 2060 in communication with a hydrauliccontrol valve 2061. The hydraulic piston 2060 can be coupled to, forexample, the clevis 43. The hydraulic control valve 2061 can providepressure to ports 2062 and 2063 that can facilitate the movement of thehydraulic piston 2060 to thereby move the clevis 43. The skew actuator2054 can include a pump 2064 in fluid communication with a reservoir2065. The pump 2064 can supply pressurized control fluid to a pressurerelief valve 2066 and an accumulator 2067 that are adapted to supplypressure control fluid to the hydraulic control valve 2061. In someembodiments, the hydraulic control valve 2061 is a four-way directionalcontrol valve that can be in communication with a spool actuator 2068.The spool actuator 2068 can be configured to adjust the hydrauliccontrol valve 2061 based at least in part on a desired skew condition ofthe CVT 1000, for example. In one embodiment, the spool actuator 2068can be an electronic servo actuator (not shown). In some embodiments,the spool actuator 2068 can be a manual lever (not shown). In otherembodiments, the hydraulic control valve 2061 can be provided with atranslatable housing to facilitate an adjustment of the ports 2069 withrespect to the internal spool (not shown). The translatable housing canbe configured to compensate for steady state errors that may occurduring operation of the skew actuator 2054 or during operation of theCVT 1000.

Referring now to FIG. 29A, in one embodiment the control module 2056includes a control device 2070, a communication device 2072, and amicroprocessor 2074. In some embodiments, the control device 2070 can beconfigured to perform a control process such as a well-knownproportional/integral gain control process based on a setpoint signal2076 and a feedback signal 2078. In one embodiment, the setpoint signal2076 can be configured to represent a desired input speed. In someembodiments, the setpoint signal 2076 can be configured to represent adesired speed ratio of, for example, the CVT 2051. In other embodiments,the setpoint signal 2076 can be configured to represent a desired outputspeed, a desired input torque, and/or a desired output torque, or anyother desired operating characteristic of the CVT 2051. The feedbacksignal 2078 can be configured to provide an indication of the currentoperating condition of the CVT 2051. In one embodiment, the feedbacksignal 2078 is configured to represent the actual speed of the CVT 2051.In some embodiments, the feedback signal 2078 is configured to representthe actual speed ratio of the CVT 2051. In other embodiments, thefeedback signal 2078 is configured to provide an indication of theactual output speed, the actual output torque, and/or the actual inputtorque of the CVT 2051. The control device 2070 can be configured tocooperate with a communication device 2072. The communication device2072 can include communication hardware such as serial devices, forexample, RS232 devices, USB devices, or other well-known communicationhardware. The communication device 2072 can be adapted to cooperate witha microprocessor 2074. The microprocessor 2074 can generate an actuatorcommand signal 2080 based at least in part on the setpoint signal 2076and/or the feedback signal 2078. In one embodiment, the microprocessor2074 includes hardware configured to operate power electronics incommunication with any one or more of the skew actuator 2054, the CVT2051, the prime mover 2052, and/or the load 2053.

Referring now to FIG. 29B, in one embodiment a skew control process 2100can be implemented on, for example, a microprocessor in communicationwith power electronics hardware of the CVT 1000. In some embodiments,the skew-based control process 2000 can be implemented on amicroprocessor in communication with the CVT 12 or other CVT embodimentsdescribed herein. The skew-based control process 2100 begins at a block2101. The skew-based control process 2100 then proceeds to a block 2102where a desired tilt angle (γ) set point for the traction planetassemblies 1024 of the CVT 1000, for example, is received. Theskew-based control process 2100 continues to a block 2103 where acommand signal for a skew actuator is determined. In one embodiment, thecommand signal is determined by a well-known gain (sometimes referred toas a “PI” or “PID”) control process. Next, the skew-based controlprocess 2100 moves to an actuator subprocess 2104 where the commandsignal is applied to the skew actuator 2054, for example. Uponcompletion of the actuator subprocess 2104, the skew-based controlprocess 2100 proceeds to a block 2105 where the tilt angle (γ) of thetraction planet assembly 1024 is measured. In one embodiment, the actualtilt angle (γ) of the traction planet assembly 1024 can be determined byusing a proximity sensor or other device adapted to provide anindication of the actual tilt angle tilt angle (γ) of the tractionplanet assemblies 1024. Next, the skew-based control process 2100proceeds to a decision block 2106 where the measured tilt angle tiltangle (γ) is compared to the desired tilt angle tilt angle (γ) set pointto thereby form a comparison value. If the measured tilt angle (γ) isnot equal to the desired tilt angle (γ) set point, the skew-basedcontrol process 2100 returns to the block 2103. If the measured tiltangle (γ) is equal to the desired tilt angle (γ) set point, theskew-based control process 2100 proceeds to an end block 2107. Theskew-based control process 2100 remains at the end block 2107 until anew tilt angle (γ) set point is received. In some embodiments, theskew-based control process 2100 is configured to operate in an open loopmanner; in such a case, the blocks 2105 and 2106 are not included in theskew-based control process 2100.

Referring now to FIG. 29C, in one embodiment a skew control process 2110can be implemented on, for example, a microprocessor in communicationwith power electronics hardware of the CVT 1000. In some embodiments,the skew-based control process 2110 can be implemented on amicroprocessor in communication with the CVT 12 or other CVT embodimentsdescribed herein. The skew-based control process 2110 begins at a block2111. The skew-based control process 2110 then proceeds to a block 2112where a desired output speed set point of the CVT 1000 is received. Theskew-based control process 2110 continues to a block 2113 where acommand signal for a skew actuator is determined. In one embodiment, thecommand signal is determined by a well-known PI control process. Next,the skew-based control process 2110 moves to an actuator subprocess 2114where the command signal is applied to the skew actuator 2054, forexample. Upon completion of the actuator subprocess 2114, the skew-basedcontrol process 2110 proceeds to a block 2115 where the output speed ofthe CVT 1000 is measured. In one embodiment, the output speed of the CVT1000 can be determined by using a speed sensor configured to measure aspeed indicative of the output speed of the CVT 1000. Next, theskew-based control process 2110 proceeds to a decision block 2116 wherethe measured output speed is compared to the desired output speed setpoint to thereby form a comparison value. If the measured output speedis not equal to the desired output speed set point, the skew-basedcontrol process 2110 returns to the block 2113. If the measured outputspeed is equal to the desired output speed set point, the skew-basedcontrol process 2110 proceeds to an end block 2117. The skew-basedcontrol process 2110 remains at the end block 2117 until a new outputspeed set point is received. In some embodiments, the skew-based controlprocess 2110 is configured to operate in an open loop manner; in such acase, the blocks 2115 and 2116 are not included in the skew-basedcontrol process 2110.

Referring now to FIG. 29D, in one embodiment a skew control process 2120can be implemented on, for example, a microprocessor in communicationwith power electronics hardware of the CVT 1000. In some embodiments,the skew-based control process 2120 can be implemented on amicroprocessor in communication with the CVT 12 or other CVT embodimentsdescribed herein. The skew-based control process 2120 begins at a block2121. The skew-based control process 2120 then proceeds to a block 2122where a desired input speed set point of the CVT 1000 is received. Theskew-based control process 2120 continues to a block 2123 where acommand signal for a skew actuator is determined. In one embodiment, thecommand signal is determined by a well-known PI control process. Next,the skew-based control process 2120 moves to an actuator subprocess 2124where the command signal is applied to the skew actuator 2054, forexample. Upon completion of the actuator subprocess 2124, the skew-basedcontrol process 2120 proceeds to a block 2125 where the input speed ofthe CVT 1000 is measured. In one embodiment, the input speed of the CVT1000 can be determined by using a speed sensor configured to measure aspeed indicative of the input speed of the CVT 1000. Next, theskew-based control process 2120 proceeds to a decision block 2126 wherethe measured input speed is compared to the desired input speed setpoint to thereby form a comparison value. If the measured input speed isnot equal to the desired input speed set point, the skew-based controlprocess 2120 returns to the block 2123. If the measured input speed isequal to the desired input speed set point, the skew-based controlprocess 2120 proceeds to an end block 2127. The skew-based controlprocess 2120 remains at the end block 2127 until a new output speed setpoint is received. In some embodiments, the skew-based control process2120 is configured to operate in an open loop manner; in such a case,the blocks 2125 and 2126 are not included in the skew-based controlprocess 2120.

Passing now to FIGS. 30-33, in one embodiment a CVT 3000 can include afirst housing member 3002 coupled to a second housing member 3004. Thefirst housing member 3002 can be provided on a first end with a flange3006. The flange 3006 can facilitate the coupling of the CVT 3000 to,for example, an electric drive motor (not shown). In some embodiments,the CVT 3000 can couple to a crank shaft of an internal combustionengine (not shown). The CVT 3000 can include a skew actuator 3005coupled to a skew driver 3007. The skew actuator 3005 and the skewdriver 3007 can be adapted to facilitate an adjustment in the skewcondition and consequently the operating condition of the CVT 3000. Insome embodiments, the skew actuator 3005 can be in communication with askew control system (not shown).

In one embodiment, the CVT 3000 is provided with a main shaft 3008 thatcan be configured to be substantially aligned with a longitudinal axis3010 of the CVT 3000. The main shaft 3008 can couple to an input driver3012 and to a planetary driver 3014. In one embodiment, the main shaft3008 can be adapted to couple to certain components of a pump 3015. Inone embodiment, the pump 3015 is a well known gearotor-type pump. In oneinstance, the pump 3015 includes an inner gear configured to be drivenby the main shaft 3008. The pump 3015 can also include a housingconfigured to be substantially non-rotatable about the longitudinal axis3010. The pump 3015 can be configured to provide lubrication to the CVT.In some embodiments, the pump 3015 can be configured to supply apressurized hydraulic fluid to, for example, a control system on anaircraft. The planetary driver 3014 can be configured to couple to aplanetary gear assembly 3016. In one embodiment, the planetary gearassembly 3016 can be a dual pinion planetary gear set having a sun gear,a set of planet gears, a carrier, and a ring gear. In some embodiments,the planetary driver 3014 can be coupled to the carrier of the planetarygear assembly 3016.

Still referring to FIGS. 30-33, in one embodiment the CVT 3000 isprovided with a first traction ring 3018 coupled to the input driver3012. The first traction ring 3018 is in contact with a variatorassembly 3020. The CVT 3000 can be provided with a second traction ring3022 in contact with a variator assembly 3020. The second traction ring3022 can be coupled to an axial force generator assembly 3024. In oneembodiment, the axial force generator assembly 3024 includes a number ofrollers configured to cooperate with a number of ramps to produce axialforce during operation of the CVT 3000. The axial force generatorassembly 3024 can be coupled to a planetary sun driver 3026. Theplanetary sun driver 3026 can be coupled to the sun gear of theplanetary gear assembly 3016. In one embodiment, the planetary gearassembly 3016 can be coupled to an output shaft 3028. In someembodiments, the output shaft 3028 is coupled to the ring gear of theplanetary gear assembly 3016.

During operation of the CVT 3000, an input power can be supplied to theCVT 3000 via a coupling to the main shaft 3008. The main shaft 3008 cantransfer power to the input driver 3012 and to the planetary driver3014. The input driver 3012 can be configured to transfer power to thefirst traction ring 3018 to thereby deliver power to the variatorassembly 3020. The variator assembly 3020 transfers power to the secondtraction ring 3022. The second traction ring 3022 transfers power to theplanetary sun driver 3026. In one embodiment, the power delivered to theplanetary gear assembly 3016 through the planetary driver 3014 and theplanetary sun driver 3026 is transferred out of the CVT 3000 through theoutput shaft 3028.

Referring now to FIGS. 34 and 35, in one embodiment a variator assembly3020 includes a number of traction planet assemblies 3030 arrangedangularly about the longitudinal axis 3010. Each traction planetassembly 3030 is adapted to contact a traction sun 3032 at a radiallyinward location. The traction sun 3032 is operably coupled to a set ofshift cams 3034. In one embodiment, the traction sun 3032 and the shiftcams 3034 are adapted to translate axially along the longitudinal axis3010 during operation of the CVT 3000. The shift cams 3034 can beconfigured to couple to each of the traction planet assemblies 3030. Inone embodiment, the variator assembly 3020 is provided with a firstcarrier member 3036 and a second carrier member 3038. The first andsecond carrier members 3036 and 3038 are configured to support each ofthe traction planet assemblies 3030. In one embodiment, the secondcarrier member 3038 is configured to rotate with respect to the firstcarrier member 3036. The first and second carrier members 3036 and 3038can be coupled to the skew driver 3007. The first and second carriermembers 3036 and 3038 can be coupled to a first carrier cap 3040 and asecond carrier cap 3042, respectively. The first and second carrier caps3040 and 3042 are configured to couple to each of the traction planetassemblies 3030. The first and second carrier caps 3040 and 3042 can beattached to the first and second carrier members 3036 and 3038 withclips 3044.

Referring specifically now to FIG. 35, in one embodiment the variatorassembly 3020 is provided with a number of carrier inserts 3046. Thecarrier inserts 3046 can be adapted to attach to the first and secondcarrier members 3036 and 3038. Once assembled, the carrier inserts 3046can contact certain components of the traction planet assemblies 3030.In one embodiment, the carrier inserts 3046 are made of steel and thefirst and second carrier members 3036, 3038 are made of aluminum. Insome embodiments, the carrier inserts 3046 are integral to the first andsecond carrier members 3036, 3038.

Turning now to FIGS. 36 and 37, in one embodiment the traction planetassembly 3030 includes a substantially spherical traction planet 3048having a central bore adapted to receive a planet axle 3050. Thetraction planet 3048 can be coupled to the planet axle 3050 withbearings 3052. The traction planet assembly 3030 can include a first leg3054 coupled to a first end of the planet axle 3050. The traction planetassembly 3030 can include a second leg 3056 coupled to a second end ofthe planet axle 3050, wherein the second end of the planet axle is at adistal location from the first end. The first and second legs 3054 and3056 can each be adapted to receive a reaction roller 3058. In oneembodiment, the reaction roller 3058 is received in a slot 3060 providedin each leg 3054, 3056. In one embodiment, the first leg 3054 can beattached to the planet axle 3050 with a press fit or by other suitablerigid coupling method. The roller 3058A can be configured to rotateabout the planet axle 3050. In some embodiments, the second leg 3056 canbe configured to rotate with respect to the planet axle 3050. The roller3058B can be attached to the planet axle 3050 with a press fit or byother suitable rigid coupling methods, to thereby axially retain thesecond leg 3056 on the planet axle 3050. The rollers 3058 are configuredto couple to the carrier members 3036 and 3038. In one embodiment, eachof the first and second legs 3054 and 3056 are provided with a shiftreaction roller 3062. The shift reaction roller 3062 can be received ina slot 3064 formed in each of the first and second legs 3054, 3056. Inone embodiment, the slot 3064 is substantially perpendicular to the slot3060. The shift reaction roller 3062 can be adapted to receive a shiftroller axle 3066. The shift roller axle 3066 can be received in a bore3068. During operation of the CVT 3000, the shift reaction rollers 3062couple to the shift cams 3034.

Referring still to FIGS. 36 and 37, in one embodiment the first andsecond legs 3054 and 3056 are provided with a bore 3070 adapted toreceive the planet axle 3050. The bore 3070 can be substantiallyperpendicular to the slot 3060. The first and second legs 3054 and 3056can be provided with a shoulder 3072. The shoulder 3072 can besubstantially aligned with, and extend from, the bore 3070. In oneembodiment, the shoulder 3072 is configured to cooperate with thebearings 3052. The first and second legs 3054 and 3056 can be providedwith a reaction surface 3074. The reaction surface 3074 can have acurved profile when viewed in the plane of the page of FIG. 37. Thereaction surfaces 3074 can be adapted to slidingly engage the carriercaps 3040, 3042.

Passing now to FIG. 38, in one embodiment the carrier insert 3046 canhave a substantially u-shaped body 3076. The carrier insert 3046 canhave a reaction surface 3078 formed on the interior of the u-shaped body3076. The reaction surface 3078 is configured to contact the roller 3058during operation of the CVT 3000. The carrier insert 3046 can have anexterior surface 3080. The exterior surface 3080 is adapted to attach tothe first or second carrier member 3036 or 3038.

Referring now to FIGS. 39 and 40, in one embodiment the second carriermember 3038 can be a substantially bowl-shaped body 3082 having acentral bore 3084. The bowl-shaped body 3082 can be provided with anumber of radial slots 3086 arranged angularly about the central bore3084. Each of the radial slots 3086 can have skew reaction surfaces 3088configured to contact the rollers 3058. The second carrier member 3038can be provided with a shoulder 3090 extending axially from the centralbore 3084. The shoulder 3090 can be provided with a groove 3092 adaptedto receive the clip 3044. The bowl shaped body 3082 can be provided witha substantially flat face 3094 formed about the outer periphery. Theface 3094 can be configured to provide a sliding interface between thefirst and second carrier members 3036 and 3038. The second carriermember 3038 can be provided with a tab 3094 extending radially from theouter periphery of the bowl-shaped body 3082. The tab 3094 can beprovided with an elongated hole 3095. The elongated hole 3095 can beconfigured to cooperate with the skew driver 3007 to provide a rotationof the second carrier member 3038 with respect to the first carriermember 3036 to thereby adjust the speed ratio during operation of theCVT 3000. In one embodiment, the first housing member 3002 is providedwith a cavity 3096 (FIGS. 30 and 31) configured to surround the tab 3094and facilitate the coupling of the first and second carrier members 3036and 3038 to the skew driver 3007. In some embodiments, the first carriermember 3036 is substantially similar to the second carrier member 3038.The first carrier member 3036 can be provided with a bore 3098 (FIG.34). Upon assembly of the CVT 3000, the bore 3098 can be arranged tosubstantially align with the elongated hole 3095 and can be adapted tocooperate with the skew driver 3007.

Turning now to FIGS. 41 and 42, in one embodiment the skew driver 3007can be a substantially cylindrical rod 3100 having a first end 3102 anda second end 3104. The first end 3102 can be configured to facilitatethe coupling of the skew driver 3007 to the skew actuator 3005 (FIG.30). In some embodiments, the first end 3102 is provided with a set ofthreads adapted to couple to the skew actuator 3005. In otherembodiments, the first end 3102 is provided with a spline configured tocouple to the skew actuator 3005. The second end 3104 can be adapted tocouple to the first carrier member 3036. In some embodiments, the secondend 3104 is configured to rotate in the bore 3098 of the first carriermember 3036. The skew driver 3007 can be provided with an eccentric skewcam 3106 formed in proximity to the second end 3104. The eccentric skewcam 3106 can be arranged to have a center 3108 that is radially offsetfrom a center 3110 of the cylindrical rod 3100. The eccentric skew cam3106 can be configured to couple to the elongated hole 3095 of thesecond carrier member 3038 (FIG. 39). The eccentric skew cam 3106 isconfigured to slidingly engage the elongated hole 3095.

During operation of the CVT 3000, the skew driver 3007 can be rotated bythe skew actuator 3007. The rotation of the skew driver 3007 tends tomotivate a rotation of the second carrier member 3038 with respect tothe first carrier member 3036. The rotation of the second carrier member3038 with respect to the first carrier member 3036 induces a skewcondition on each of the traction planet assemblies 3030. The skewcondition tends to motivate a tilt in the planet axles 3050 of thetraction planet assemblies 3030. The tilting of the planet axles 3050adjusts the speed ratio of the CVT 3000.

Passing now to FIG. 43, in one embodiment a CVT 4000 can include anumber of traction planets 4002 arranged angularly about a longitudinalaxis. The CVT 4000 can be provided with a traction sun 4003 configuredto contact each traction planet 4002 at a radially inward location. Eachof the traction planets 4002 can be provided with a tiltable axis ofrotation 4004 configured to be supported by first and second carriermembers 4006 and 4008. In some embodiments, the first and second carriermembers 4006 and 4008 are adapted to facilitate a skew condition on eachof the traction planets 4002. In one embodiment, the first carriermember 4006 is substantially non-rotatable about the longitudinal axisof the CVT 4000. The CVT 4000 can include first and second tractionrings 4010, 4012 in contact with each of the traction planets 4002. Thefirst and second traction rings 4010, 4012 can be coupled to first andsecond axial force generators 4014, 4016, respectively. The first axialforce generator 4014 can be coupled to an input driver 4018. The secondaxial force generator 4016 can be coupled to an output shaft 4020. Inone embodiment, the input driver 4018 is coupled to a clutch 4022. Theclutch 4022 can be adapted to receive an input power from, for example,an electric motor or other suitable prime mover.

During operation of the CVT 4000, the input power can be transferredfrom the clutch 4022 to the input driver 4018. The input driver 4018delivers power to the first traction ring 4010 through the first axialforce generator 4014. The first traction ring 4010 transfers power toeach of the traction planets 4002. The traction planets 4002 transferpower to the second traction ring 4012. The power is delivered from thesecond traction ring 4012 to the output shaft 4020 via the second axialforce generator 4016. In some embodiments, the output shaft 4020 isconfigured to supply power to a load 4024.

Turning now to FIG. 44, in one embodiment a CVT 4100 can include anumber of traction planets 4102 arranged angularly about a longitudinalaxis. The CVT 4100 can be provided with a traction sun 4103 configuredto contact each traction planet 4102 at a radially inward location. Eachof the traction planets 4102 can be provided with a tiltable axis ofrotation 4104. The traction planets 4102 can be adapted to couple tofirst and second carrier members 4106 and 4108 respectively. In oneembodiment, the first and second carrier members 4106 and 4108 areconfigured to facilitate a skew condition on each of the tractionplanets 4102. In one embodiment, the first and second carrier members4106 and 4108 are configured to rotate about the longitudinal axis ofthe CVT 4100. The CVT 4100 can include first and second traction rings4110 and 4112, respectively. The first and second traction rings 4110and 4112 can be coupled to first and second axial force generators 4114and 4116, respectively. In one embodiment, the first axial forcegenerator 4114 is configured to be substantially non-rotatable withrespect to the longitudinal axis of the CVT 4100. The second axial forcegenerator 4116 can be coupled to an output shaft 4118.

During operation of the CVT 4100, the first carrier member 4106 can beadapted to receive a power from an input shaft 4120. The first carriermember 4106 delivers the power to each of the traction planets 4102. Thetraction planets 4102 orbit the traction sun 4103 and transfer power tothe second traction ring 4112. The power is transferred from the secondtraction 4112 to the output shaft via the second axial force generator4116. The output shaft 4118 is adapted to supply power to a load 4122.

Passing now to FIGS. 45-48, in one embodiment a variator 4200 caninclude a traction sun assembly 4202 coupled to a number of tractionplanet subassemblies 4204. The variator 4200 can be configured to beused in, for example, the CVT 12, the CVT 1000, or the CVT 3000. Each ofthe traction planet subassemblies 4204 are operably coupled to a firstcarrier member 4206 and a second carrier member 4208. In someembodiments, a carrier retaining ring 4210 can attach to the first andsecond carrier members 4206 and 4208. The traction sun subassembly 4204can include a traction sun 4212. The traction sun 4212 can have acentral bore 4214 adapted to receive bearings 4216. The central bore4214 can be provided with a shoulder 4218 and a c-clip groove 4220 tofacilitate the coupling of the bearings 4216 to the central bore 4214.The traction sun 4212 can be provided with a number of lubricantpassages 4222 extending radially outward from the central bore 4214. Inone embodiment, an outer periphery of the traction sun 4214 is providedwith first and second contact surfaces 4224A and 4224B extending from avalley 4226. The first and second contact surfaces 4224A and 4224B cancontact each of the traction planet subassemblies 4204. The first andsecond contact surfaces 4224A and 4224B can extend from the valley 4226at an angle 4228 when viewed in cross-section in the plane of FIG. 48.In one embodiment, the angle 4228 is in the range of about 2 degrees to45 degrees. In a preferred embodiment, the angle 4228 is about 5 degreesto 10 degrees. During operation of the variator 4200, the traction sunassembly 4202 is adapted to remain axially coupled to the tractionplanet subassemblies 4204 as the traction planet subassemblies 4204tilt. In some embodiments, the bearings 4216 may be removed so that thesun assembly 4202 is no longer coupled to the central bore 4214, butremains radially coupled to the CVT 1000, for example, by contacting thetraction planet assemblies 4204 through the contact surfaces 4224.

Turning now to FIGS. 49-51, in one embodiment a gear 5000 can be coupledto a first carrier member 5002 and to a second carrier member 5004. Thegear 5000 can facilitate a rotation about a longitudinal axis betweenthe first and second carrier members 5002, 5004. The gear 5000 can beprovided with a shaft 5006. The shaft 5006 can extend radially outwardfrom the first and second carrier members 5002, 5004. The shaft 5006 canbe configured to couple to a skew actuator (not shown). In someembodiments, the gear 5000 can be a conical gear and the first andsecond carrier member 5002, 5004 can be adapted to accommodate theconical gear appropriately. During operation, the skew actuator cantransmit a rotation to the shaft 5006 to thereby turn the gear 5000. Theturning of the gear 5000 tends to rotate the first carrier member 5002in a first rotational direction and tends to rotate the second carriermember 5004 in a second rotational direction substantially opposite tothat of the first rotational direction.

Referring specifically now to FIGS. 50 and 51, in one embodiment a skewdriver 5010 can be coupled to a first carrier member 5012 and to asecond carrier member 5014. The first and second carrier members 5012,5014 can be substantially similar to the first and second carriermembers 5002, 5004. The first carrier member 5012 can be provided withthreads to engage the skew driver 5010 at a first threaded interface5016. The second carrier member 5014 can be provided with threads toengage to the skew driver 5010 at a second threaded interface 5018. Thefirst threaded interface 5018 is typically a right-handed thread, whilethe second threaded interface 5018 is a left-handed thread. In oneembodiment, the skew driver 5010 can be coupled to a skew actuator (notshown). In some embodiments, the skew driver 5010 is positioned to betangent to the first and second carrier members 5012, 5014. Duringoperation, the skew driver 5010 can be rotated to thereby induce arelative rotation between the first and second carrier members 5012,5014. The threaded interfaces 5016 and 5018 can be adapted toaccommodate a small radial displacement to facilitate the rotation ofthe first and second carrier member 5012, 5014 with respect to eachother.

Referring specifically now to FIG. 52, in one embodiment a gear 5020 canbe coupled to a first carrier member 5022 and to a second carrier member5024. For clarity, the gear 5020 is shown in FIG. 52 without well-knowngear teeth. The gear 5020 can facilitate a rotation about a longitudinalaxis between the first and second carrier members 5022, 5024. The gear5020 can be provided with a shaft 5026. The shaft 5026 can be configuredto couple to a skew actuator (not shown). In one embodiment, the shaft5026 extends axially from the gear 5020. The first carrier member 5022can be provided with an engagement extension 5028 adapted to contact thegear 5020. During operation, the skew actuator can transmit a rotationto the shaft 5026 to thereby turn the gear 5020. The turning of the gear5020 tends to rotate the first carrier member 5022 in a first rotationaldirection and tends to rotate the second carrier member 5024 is a secondrotational direction substantially opposite to that of the firstrotational direction.

It should be noted that the description above has provided dimensionsfor certain components or subassemblies. The mentioned dimensions, orranges of dimensions, are provided in order to comply as best aspossible with certain legal requirements, such as best mode. However,the scope of the inventions described herein are to be determined solelyby the language of the claims, and consequently, none of the mentioneddimensions is to be considered limiting on the inventive embodiments,except in so far as anyone claim makes a specified dimension, or rangeof thereof, a feature of the claim.

The foregoing description details certain embodiments of the invention.It will be appreciated, however, that no matter how detailed theforegoing appears in text, the invention can be practiced in many ways.As is also stated above, it should be noted that the use of particularterminology when describing certain features or aspects of the inventionshould not be taken to imply that the terminology is being re-definedherein to be restricted to including any specific characteristics of thefeatures or aspects of the invention with which that terminology isassociated.

1. A continuously variable accessory drive (CVAD) comprising: acontinuously variable transmission (CVT) coupled to an accessory deviceand having a longitudinal axis, the CVT comprising: a plurality oftraction planets, each traction planet adapted to rotate about atiltable axis; a first carrier member comprising a plurality of radiallyoffset slots formed in the first carrier member and arranged angularlyabout the longitudinal axis; and a second carrier member comprising aplurality of radial slots formed in the second carrier member andarranged angularly about the longitudinal axis, the second carriermember being coupled to the first carrier member, the first and secondcarrier members operably coupled to each traction planet, wherein thefirst carrier member is configured to rotate relative to the secondcarrier member about the longitudinal axis; and a skew actuator operablycoupled to the CVT, the skew actuator adapted to apply a skew conditionto the CVT to tilt the axes of the traction planets, wherein the skewactuator comprises a hydraulic piston.
 2. The CVAD of claim 1, whereinthe skew actuator further comprises a hydraulic control valve in fluidcommunication with the hydraulic piston.
 3. The CVAD of claim 2, whereinthe skew actuator further comprises a spool actuator coupled to thehydraulic control valve, the spool actuator configured to adjust thehydraulic control valve based at least in part on a desired skewcondition of the CVT.
 4. The CVAD of claim 1, further comprising anoutput arranged along the longitudinal axis of the CVT, the outputconfigured to couple the CVAD to the accessory device.
 5. The CVAD ofclaim 4, further comprising an alternator coupled to the output.
 6. TheCVAD of claim 4, further comprising a pump coupled to the output.
 7. TheCVAD of claim 1, wherein the CVT is configured to receive an input powerfrom a pulley driven by a prime mover.
 8. A skew actuator for acontinuously variable accessory drive (CVAD) having a skew controlsystem, the skew actuator comprising: a hydraulic piston coupled to theCVT; a hydraulic control valve in fluid communication with the hydraulicpiston; and a spool actuator coupled to the hydraulic control valve, thespool actuator configured to adjust the hydraulic control valve based atleast in part on a desired skew condition of the CVT.
 9. The skewactuator of claim 8, wherein the hydraulic control valve comprising ahousing and a spool, the housing configured to translate with respect tothe spool.
 10. The skew actuator of claim 8, wherein the hydraulicpiston is operably coupled to a first carrier member of the CVAD, thefirst carrier member comprising a plurality of radially offset slotsformed in the first carrier member and arranged angularly about alongitudinal axis of the CVAD.
 11. The skew actuator of claim 8, furthercomprising a pump in fluid communication with the hydraulic controlvalve.
 12. The skew actuator of claim 11, further comprising anaccumulator in fluid communication with the pump.
 13. The skew actuatorof claim 8, wherein the hydraulic valve is a four-way directionalcontrol valve.
 14. A skew control system for a continuously variableaccessory drive (CVAD) having a plurality of traction planets, the skewcontrol system comprising: a sensor configured to receive data from aCVAD; a skew actuator configured to communicate with a control module,the skew actuator further configured to apply a skew condition to eachof the traction planets in the CVAD; and a skew controller incommunication with the control module, the skew controller configured todetermine a skew actuator command signal based at least in part on asignal from the sensor, wherein the skew actuator command signal isconfigured to control an output speed of a CVAD.
 15. The skew controlsystem of claim 14, wherein the sensor is configured to communicate withan accessory device.
 16. The skew control system of claim 14, whereinthe skew actuator comprises a servo motor.
 17. The skew control systemof claim 14, wherein the skew actuator comprises a hydraulic controlvalve.
 18. The skew control system of claim 17, wherein the hydrauliccontrol valve is a four-way directional control valve.
 19. The skewcontrol system of claim 14, wherein the skew actuator comprises a lever.20. The skew control system of claim 14, wherein the skew actuator isoperably coupled to a first carrier member of the CVAD, the firstcarrier member comprising a plurality of radially offset slots formed inthe first carrier member and arranged angularly about a longitudinalaxis of the CVAD.